feat(debug): GUI toggle for DRED verbose logs + macOS mic permission

DRED verbose logs (off by default — keeps logcat clean in normal use):
- wzp-codec: DRED_VERBOSE_LOGS atomic flag with dred_verbose_logs() /
  set_dred_verbose_logs() helpers
- opus_enc: gate "DRED enabled" + libopus version logs behind the flag
- desktop/src-tauri/engine.rs: gate DredRecvState parse log,
  reconstruction log, classical PLC log, and DRED-counter fields in
  the Android recv heartbeat (non-verbose path still logs basic recv
  stats)
- Tauri commands set_dred_verbose_logs / get_dred_verbose_logs
- Settings panel gets a "DRED debug logs (verbose, dev only)"
  checkbox; preference persists in wzp-settings localStorage and is
  pushed to Rust on save and on app boot

macOS mic permission:
- Add desktop/src-tauri/Info.plist with NSMicrophoneUsageDescription.
  Without it, modern macOS silently denies CoreAudio capture for
  ad-hoc-signed Tauri builds — capture starts but every callback
  hands you zeros. Symptom: phones could not hear desktop client,
  desktop could still hear phones (playout has no TCC gate). The
  Tauri 2 bundler auto-merges this file into WarzonePhone.app's
  Contents/Info.plist on the next build, so first launch will pop
  the standard mic prompt.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

desktop/src-tauri/Info.plist

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <!--
+      Custom Info.plist keys merged into the bundled WarzonePhone.app by
+      tauri-bundler. The base Info.plist (CFBundleIdentifier, version,
+      etc.) is generated from tauri.conf.json — only put *additional*
+      keys here.
+
+      NSMicrophoneUsageDescription is required by macOS TCC for any
+      app that opens an audio input unit. Without this string the OS
+      silently denies CoreAudio capture (input callbacks return zeros)
+      and the app never appears in System Settings → Privacy &
+      Security → Microphone. This was the root cause of the desktop
+      mic regression where phones could not hear the desktop client.
+    -->
+    <key>NSMicrophoneUsageDescription</key>
+    <string>WarzonePhone needs microphone access to transmit your voice during calls.</string>
+</dict>
+</plist>