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.

src/network/EnhancedSecureWebRTCManager.js

@@ -12345,10 +12345,10 @@ async processMessage(data) {
         }
     }
     // Public method to send files
-    async sendFile(file) {
+    async sendFile(file, options = {}) {
         //   Enforce verification gate for file transfers
         this._enforceVerificationGate('sendFile');
-        
+
         if (!this.isConnected()) {
             throw new Error('Connection not ready for file transfer. Please ensure the connection is established.');
         }
@@ -12371,7 +12371,7 @@ async processMessage(data) {
 
 
         try {
-            const fileId = await this.fileTransferSystem.sendFile(file);
+            const fileId = await this.fileTransferSystem.sendFile(file, options);
             return fileId;
         } catch (error) {
             this._secureLog('error', 'File transfer error:', { errorType: error?.constructor?.name || 'Unknown' });