feat(files): @shade/files 0.3.0 — E2EE filesystem RPC primitive

M-Files-1..6 land the full files-RPC layer + everything 0.3.0 needs to
ship. Apps keep their own UI; this layer ships the typed RPC, the
streams bridge for content I/O, and production hooks (rate limit,
retention, fingerprint gate, metrics).

@shade/files (NEW)
- Standard ops: list/stat/mkdir/delete/move/read/write/getThumbnail with
  Zod-validated wire schemas + clean user-handler types.
- Custom ops: typed via TypeScript declaration merging on CustomOpsMap
  + per-op Zod schemas; client.custom('app.foo', {...}) is fully typed.
- Content I/O: inline (≤ 256 KiB plaintext) base64-in-RPC; streams
  (> 256 KiB) ride @shade/transfer via userMetadata.shadeFilesWriteId
  / shadeFilesReadStreamId correlation. Server-side TransformStream
  bridges accept inbound transfers immediately (engine rejects chunks
  that arrive before accept) and park the readable for the matching
  RPC.
- Directory ops: walk(path, opts) async-iterable depth-first walker;
  uploadDirectory()/downloadDirectory() with bounded concurrency pool
  (default 4, cap 16), aggregated progress, abort.
- Production hooks (callback-based, vendor-neutral): rate-limit (op +
  byte), idempotency cache (LRU + TTL + in-flight de-dupe), path
  policy (traversal + percent-decode hardening), fingerprint gate
  (required/optional/reject), pluggable Ed25519 sig verification with
  ±5 min replay window, onMetric sink (standard names).
- React hooks (subpath @shade/files/react): ShadeFilesProvider,
  useShadeFiles, useFileList, useFileTransfer/Upload/Download.
- Shade.files.serve(handler) + Shade.files.client(peer) high-level
  entrypoint in @shade/sdk; lazy + memoized; one handler per Shade.

Wire format bump
- @shade/proto wire VERSION 0x01 → 0x02. Length prefixes changed from
  u16 to u32. The previous u16 silently truncated payloads above
  64 KiB — a hard correctness ceiling that blocked inline file ops
  up to 256 KiB. Wire-incompatible with 0.2.x peers; new sessions
  only. Cross-platform Kotlin port (android/shade-android) updated to
  match; test-vectors/wire-format.json regenerated.

Concurrency safety
- ShadeSessionManager.encrypt/.decrypt now run under per-peer mutex.
  Concurrent decryptions of the same peer raced ratchet state
  (manifested as sporadic "Failed to decrypt — wrong key or tampered
  data" under load — surfaced once concurrent uploadDirectory pumped
  many writes in flight). Encrypt was already serialized via
  Shade.send's encryptChains; decrypt is now serialized at the
  manager layer too.

@shade/streams extension
- StreamMetadata.userMetadata?: Record<string, string> for
  application-level key/value pairs that round-trip verbatim through
  stream-init plaintext. Used by @shade/files for write/read
  correlation; available to any consumer.

@shade/sdk extension
- Shade.files getter (lazy + memoized).
- BackgroundHooks.onPruneFiles + periodic timer (default 5 min) +
  BackgroundTasks.setHook(name, fn) for runtime hook registration.

Bundles in-flight 0.2.0 work
- packages/shade-streams/, packages/shade-transfer/, related
  shade-sdk streams-bridge + shade-widgets transfer hooks were
  uncommitted prior to this session. Including them keeps the
  workspace consistent at 0.3.0 since @shade/files depends on them.

Tests
- 74 new tests in @shade/files (572 → 646 workspace pass; 0 fail;
  3× stable). Coverage spans unit (inline-threshold + concurrency),
  integration (read-write inline + streams up to 1 MiB, walk +
  upload/download directory, custom-op, metrics, SDK namespace
  end-to-end), and security (tampered-envelope sig verification,
  replay window, fingerprint gate, rate-limit + quota).

Release artifacts
- All packages bumped to 0.3.0 via scripts/bump-version.ts.
- scripts/publish-all.ts PACKAGES updated with shade-files in
  topological order (after shade-transfer, before shade-sdk).
- bun run publish:dry clean (14 packed, 0 failed).
- examples/08-files-browser/ — three-process CLI demo (prekey + Bob
  server + Alice CLI) covering list/stat/mkdir/delete/upload/download.
- docs/files.md — full API + design doc.
- CHANGELOG.md 0.3.0 entry.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/SHADE-BY-SCENARIO.md

@@ -0,0 +1,63 @@
+# Shade by scenario — modular E2EE toolkit
+
+This page is for **builders**, not cryptography specialists. Shade is packaged so you can **drop in small pieces** per project instead of importing a heavy “everything” stack.
+
+---
+
+## Plain-language mental model
+
+1. **Identity & session (the hard crypto):** Shade establishes a **secret channel** between two parties using the same kind of cryptographic core as Signal (initial setup + ongoing “ratchet” updates). **You mostly call high-level APIs** (`send`, `receive`, fingerprints) rather than assembling primitives by hand.
+
+2. **Who is “the server”?**  
+   The **prekey server** only helps with **public key material** (so Alice can fetch Bob’s public bundle before the first message). It is **not** your general-purpose message relay unless **you** build that separately. Normal **message payloads and file chunks** typically flow over **your** transport (your HTTP routes, websocket, bridge, queue, etc.).
+
+3. **Small vs large payloads:**  
+   Short messages ride the usual ratchet envelopes. Very large payloads use **Streams + Transfer**: secrets are negotiated over the ratchet; ** ciphertext chunks** ship over optimized HTTP/WebSocket transports with parallelism and resume.
+
+4. **Trust:** Strong encryption does **not** replace **verifying who you are talking to**. For high-stakes use, compare **safety numbers** out-of-band (see [THREAT-MODEL.md](../THREAT-MODEL.md)).
+
+---
+
+## Scenario → minimum packages
+
+Pull in **one row** that matches your project; add optional columns only when needed.
+
+| Scenario | What you need | Minimum packages / surface | Where to start |
+|----------|----------------|----------------------------|----------------|
+| **Backend or Bun service** — encrypted messages between users | Session storage + crypto provider + prekey URL | `@shade/sdk` + `sqlite:` or `@shade/storage-postgres` | `createShade()` → `send` / `receive` |
+| **Browser / frontend** — same, in the client | Web crypto + durable or memory storage | `@shade/sdk` or `@shade/core` + `@shade/crypto-web` (+ storage you provide) | Same APIs; ensure `prekeyServer` is reachable from the browser (CORS, etc.) |
+| **Large files** — resumable E2EE upload/download | Above + stream protocol + HTTP (or WS) transport | `@shade/sdk` (re-exports transfer) + mount transfer routes on **your** HTTP server | `shade.upload` / `onIncomingTransfer` — see [streams.md](./streams.md) |
+| **React UI** — upload/download widgets | Runtime from SDK + widgets | `@shade/sdk` + `@shade/widgets` | `ShadeRuntimeProvider`, `useShadeUpload` / `useShadeDownload` |
+| **Prekey hosting only** — one container per product | No app crypto in the container | Docker image / `@shade/server` | Deploy prekey image; point `prekeyServer` at it from apps |
+| **Maximum control** — custom wire, custom transport | Wire + session manager | `@shade/core` + `@shade/proto` (+ your storage + crypto provider) | `ShadeSessionManager`, encode/decode envelopes yourself |
+| **HTTP or WebSocket convenience** | Auto-wrap application bytes | `@shade/transport` on top of your stack | Use when you want transport helpers, not a new protocol |
+| **Android** | Byte-compatible with TS (roadmap) | `shade-android` module | See [android/shade-android/README.md](../android/shade-android/README.md) — parity work in progress |
+
+You can **mix rows**: e.g. backend with `@shade/sdk` + SQLite for sessions, separate service mounting `transfer` routes, browser clients using `@shade/widgets`.
+
+---
+
+## New project checklist (lightweight)
+
+1. Run a **prekey server** (Docker or embedded `@shade/server`) for your environment.
+2. Pick **storage** (`sqlite:…`, Postgres, or project-specific adapter implementing the core storage interfaces).
+3. Choose **surface**: usually `@shade/sdk` unless you truly need `@shade/core` only.
+4. For files: enable **transfer routes** and authenticate chunk uploads using the patterns in the SDK (see streams doc).
+5. Run **`shade doctor`** when something fails in production-ish setups (install the CLI as in repository [Quick start](../README.md#quick-start)); coverage is evolving — roadmap in [V2.2](./V2.2.md).
+
+---
+
+## Related docs & roadmap
+
+| Topic | Doc |
+|--------|-----|
+| File transfer architecture | [streams.md](./streams.md) |
+| Deployment & operations | [DEPLOYMENT.md](./DEPLOYMENT.md) |
+| Threat model | [THREAT-MODEL.md](../THREAT-MODEL.md) |
+| Planned improvements | [V2.1](./V2.1.md), feature backlog [V2.2](./V2.2.md), trust/ops [V2.3](./V2.3.md) |
+
+---
+
+## Version note
+
+This file describes how Shade is **intended** to be composed. Package names and re-exports may gain small aliases over time; the **scenario table** should remain the source of truth for “what to install for what job.” Update this page when adding major surfaces (new transport bridges, richer `shade init` templates, etc.).