Add end-to-end encrypted voice messages; release v5.4.5

- Record voice notes in-browser, sent over the chunked AES-GCM file-transfer
  channel (per-file session key + signed SHA-256 integrity).
- Captured as PCM and encoded to WAV for universal playback (incl. iOS/Safari);
  auto-accepted and played inline from an in-memory blob, never written to disk.
- Composer mic button with live waveform + timer; desktop shows mic + send side
  by side, mobile swaps mic to send when typing.
- CSP media-src now allows blob: so recorded/received audio can play.
- Roadmap: Desktop Edition -> 5.0, new 5.5 'Secure Voice & Calls', later
  milestones shifted; version bumped to 5.4.5.
- Update README, docs (security/API/cryptography), and CHANGELOG.

doc/API.md

@@ -18,6 +18,16 @@
 - `setFileTransferCallbacks(onProgress, onReceived, onError, onIncomingRequest)` updates manager fields and any live `EnhancedSecureFileTransfer` instance.
 - Passing `null` values detaches callbacks from the active transfer system.
 
+### Voice messages
+
+- `sendFile(file, options)` accepts an optional `options` object. `options.voice`
+  (`{ dur, bars }`) marks the transfer as a voice note and rides along as unsigned
+  metadata; `options.uiId` correlates progress events to a UI bubble before the
+  `fileId` resolves.
+- `onProgress` receives `{ fileId, uiId, direction, progress, isVoice, voice }`.
+  `onIncomingFileRequest` and `onReceived` include `isVoice` and `voice` so the UI
+  can auto-accept and render a voice bubble instead of a file card.
+
 ## EnhancedSecureFileTransfer
 
 ### Incoming transfers

doc/CRYPTOGRAPHY.md

@@ -2,7 +2,7 @@
 
 ## Release context
 
-- Product release: `v4.8.5`
+- Product release: `v5.4.5`
 - Protocol version: `4.1`
 
 ## Session establishment
@@ -16,6 +16,9 @@ The SAS is deterministic for both peers in the same authenticated session. Users
 - encrypted payloads are validated before decryption
 - decrypted chat text is sanitized before entering React state or the UI
 - replay and ordering controls remain part of the session layer
+- voice messages are transported over the file-transfer channel: each is
+  encrypted with a per-file AES-GCM session key and integrity-checked with a
+  signed SHA-256 hash before playback
 
 ## Local key metadata
 
@@ -23,4 +26,4 @@ Sensitive IndexedDB metadata is stored in encrypted envelopes. Legacy plaintext
 
 ## Scope note
 
-This document describes the current browser implementation behavior relevant to the v4.8.5 hardening release. It does not replace independent cryptographic review.
+This document describes the current browser implementation behavior relevant to the v5.4.5 release. It does not replace independent cryptographic review.

doc/SECURITY-ARCHITECTURE.md

@@ -10,6 +10,7 @@
 | Privacy mode | optional TURN relay-only mode |
 | Message UI safety | incoming decrypted text sanitized before display |
 | File transfer | validated metadata, explicit consent, allowlist policy |
+| Voice messages | same chunked AES-GCM transfer as files; auto-accepted and played inline |
 | Local metadata | encrypted IndexedDB envelopes with migration |
 | Lifecycle | unified disconnect cleanup and bounded resource retention |
 
@@ -42,6 +43,18 @@ The verified state is reached only when both local and remote confirmation flags
 5. sender transmits chunks only after acceptance
 6. completed received buffers are retained within a bounded window
 
+## Voice messages
+
+Voice notes reuse the file-transfer pipeline, so they inherit its per-file
+AES-GCM session key, chunking, and SHA-256 integrity check. Differences from a
+regular file:
+
+1. audio is recorded in-browser and encoded as PCM/WAV before sending
+2. duration and a downsampled waveform travel as **unsigned** presentation
+   metadata; the audio bytes remain integrity-protected by the signed file hash
+3. the receiver **auto-accepts** voice transfers (no consent prompt) and plays
+   them inline from an in-memory blob — nothing is written to disk
+
 ## Disconnect cleanup
 
 The canonical disconnect path clears: