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.

meta.json

@@ -1,10 +1,10 @@
 {
-  "version": "1782446255208",
-  "buildVersion": "1782446255208",
-  "appVersion": "4.10.0",
-  "buildTime": "2026-06-26T03:57:35.595Z",
-  "buildId": "1782446255208-db5d6e4",
-  "gitHash": "db5d6e4",
+  "version": "1784694927450",
+  "buildVersion": "1784694927450",
+  "appVersion": "5.4.5",
+  "buildTime": "2026-07-22T04:35:27.501Z",
+  "buildId": "1784694927450-0e3e3a2",
+  "gitHash": "0e3e3a2",
   "generated": true,
-  "generatedAt": "2026-06-26T03:57:35.602Z"
+  "generatedAt": "2026-07-22T04:35:27.502Z"
 }