Cross-platform distribution, UI improvements, and performance optimizations

- PyInstaller frozen sidecar: spec file, build script, and ffmpeg path resolver
  for self-contained distribution without Python prerequisites
- Dual-mode sidecar launcher: frozen binary (production) with dev mode fallback
- Parallel transcription + diarization pipeline (~30-40% faster)
- GPU auto-detection for diarization (CUDA when available)
- Async run_pipeline command for real-time progress event delivery
- Web Audio API backend for instant playback and seeking
- OpenAI-compatible provider replacing LiteLLM client-side routing
- Cross-platform RAM detection (Linux/macOS/Windows)
- Settings: speaker count hint, token reveal toggles, dark dropdown styling
- Loading splash screen, flexbox layout fix for viewport overflow
- Gitea Actions CI/CD pipeline (Linux, Windows, macOS ARM)
- Updated README and CLAUDE.md documentation

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

python/voice_to_notes/services/transcribe.py

@@ -12,6 +12,7 @@ from faster_whisper import WhisperModel
 
 from voice_to_notes.ipc.messages import progress_message
 from voice_to_notes.ipc.protocol import write_message
+from voice_to_notes.utils.ffmpeg import get_ffmpeg_path, get_ffprobe_path
 
 CHUNK_REPORT_SIZE = 10
 LARGE_FILE_THRESHOLD_SEC = 3600  # 1 hour
@@ -202,7 +203,7 @@ class TranscribeService:
         # Get total duration via ffprobe
         try:
             probe_result = subprocess.run(
-                ["ffprobe", "-v", "quiet", "-show_entries", "format=duration",
+                [get_ffprobe_path(), "-v", "quiet", "-show_entries", "format=duration",
                  "-of", "default=noprint_wrappers=1:nokey=1", file_path],
                 capture_output=True, text=True, check=True,
             )
@@ -235,7 +236,7 @@ class TranscribeService:
             tmp.close()
             try:
                 subprocess.run(
-                    ["ffmpeg", "-y", "-ss", str(chunk_start),
+                    [get_ffmpeg_path(), "-y", "-ss", str(chunk_start),
                      "-t", str(chunk_duration_sec),
                      "-i", file_path,
                      "-ar", "16000", "-ac", "1", "-c:a", "pcm_s16le",