release(v4.1.0): browser-friendly HTTP RPC for @shade/files

Default shade.files.client(peer) requires both peers to be mutually
addressable over HTTP — the response round-trips through
Shade.deliverControlEnvelope (POST to peer's /v1/transfer/control).
Browser tabs can't host an HTTP server, so they couldn't consume
@shade/files at all. Dispatch's filutforsker (admin-panel browser UI)
is the canonical use-case.

This release adds a parallel request-response transport: one POST per
RPC, encrypted envelope in the body, encrypted response in the same
HTTP response. No inbound channel needed on the client.

### New API

- shade.files.rpcRoute(opts?) — Hono app exposing POST /rpc.
- shade.files.httpClient(peer, opts) — request-response FileClient.
- FilesNamespace.serve(handler, { inlineOnly: true }) — skip streams-
  bridge (and its configureTransfers pre-condition); also skip
  channel-based dispatch so requests aren't double-dispatched.

### Limitations (v1)

Inline only (≤ 256 KiB). Streamed reads/writes throw clear errors
directing to shade.files.client(peer) on a server-to-server deploy.

### Tests

7 integration tests in tests/integration/http-rpc.test.ts covering
round-trip + negative cases (sender header, empty/garbage body,
maxBodyBytes, rpcRoute-without-serve).

### Symmetry

Mirrors @shade/server's shade-auth-middleware: encrypted envelope in
request body, decrypted via existing ratchet, response in same HTTP
roundtrip. No WebSocket, no SSE, no outbound from server.

Wire-compatible. Source-compatible. Lockstep bump to 4.1.0.

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

packages/shade-files/src/index.ts

@@ -183,6 +183,19 @@ export { MAX_SIGNATURE_AGE_MS } from './server/handler.js';
 export { createFilesNamespace } from './integration/files-namespace.js';
 export type { FilesNamespace } from './integration/files-namespace.js';
 
+// Request-response HTTP transport — for browser-style consumers
+// (one HTTP POST per RPC, no inbound channel needed). See
+// `docs/files.md § HTTP RPC`.
+export { createFilesRpcRoute } from './server/rpc-route.js';
+export type { FilesRpcRouteOptions } from './server/rpc-route.js';
+export { createFilesHttpClient } from './client/http-client.js';
+export type { FilesHttpClientOptions } from './client/http-client.js';
+
+// Shared structural surface @shade/files needs from a Shade instance —
+// exposed so consumers building custom Shade-shaped bridges can verify
+// they implement every required member.
+export type { ShadeBridge } from './integration/shade-bridge.js';
+
 // Integration helpers — wire handler + pending registry onto a channel
 export { attachFileHandler } from './integration/wire-server.js';
 export { attachClientRouting } from './integration/wire-client.js';