release(v4.9.0): relay-side encrypted blob primitive + SDK Profile namespace

Ships the Prism FR (encrypted-profile-storage-v4.9.md) as a generic
relay-side encrypted blob primitive: deterministically-located,
AEAD-sealed blobs keyed by a 32-byte slotId derived client-side via
HKDF from the user's master key. Unlocks credential-only bootstrap
of new devices into existing E2EE state — no QR, no physical access.

Server: BlobStore interface + Memory/Sqlite/Postgres impls,
createBlobRoutes for GET/PUT/DELETE /v1/blob/:slotId with TOFU pubkey
auth and If-Match CAS (409/412 semantics). Mounted on the same Hono
app as the inbox; SHADE_BLOB_PG_URL / SHADE_BLOB_DB_PATH /
SHADE_DISABLE_BLOB env-var plumbing in standalone.

SDK: createProfileNamespace high-level wrapper (HKDF derivation,
random-nonce AEAD seal, slotId-bound AAD) + low-level BlobClient.
Cross-platform test vectors in test-vectors/blob-storage.json.

New errors: ConflictError (409), PreconditionFailedError (412).

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

packages/shade-core/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@shade/core",
-  "version": "4.8.5",
+  "version": "4.9.0",
   "type": "module",
   "main": "src/index.ts",
   "types": "src/index.ts",

packages/shade-core/src/errors.ts

@@ -158,6 +158,30 @@ export class UnauthorizedError extends ShadeError {
   }
 }
 
+/**
+ * 409 Conflict — caller wrote to a resource that already exists without
+ * supplying an If-Match precondition. V4.9: the encrypted blob primitive
+ * uses this to force read-then-write on already-occupied slots.
+ */
+export class ConflictError extends ShadeError {
+  constructor(message = 'Conflict') {
+    super('SHADE_CONFLICT', message);
+    this.name = 'ConflictError';
+  }
+}
+
+/**
+ * 412 Precondition Failed — caller supplied an If-Match etag that does
+ * not match the current state. V4.9: the encrypted blob primitive uses
+ * this to surface stale-CAS so clients can re-read, merge, and retry.
+ */
+export class PreconditionFailedError extends ShadeError {
+  constructor(message = 'Precondition failed') {
+    super('SHADE_PRECONDITION_FAILED', message);
+    this.name = 'PreconditionFailedError';
+  }
+}
+
 // ─── Error → HTTP Status Mapping ────────────────────────────
 
 /**
@@ -180,7 +204,10 @@ export function errorToHttpStatus(error: unknown): number {
       return 400;
     case 'SHADE_REPLAY':
     case 'SHADE_DUPLICATE_MESSAGE':
+    case 'SHADE_CONFLICT':
       return 409;
+    case 'SHADE_PRECONDITION_FAILED':
+      return 412;
     case 'SHADE_RATE_LIMIT':
       return 429;
     case 'SHADE_TIMEOUT':