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/utils/ffmpeg.py

@@ -0,0 +1,43 @@
+"""Resolve ffmpeg/ffprobe paths for both frozen and development builds."""
+
+from __future__ import annotations
+
+import os
+import sys
+
+
+def get_ffmpeg_path() -> str:
+    """Return the path to the ffmpeg binary.
+
+    When running as a frozen PyInstaller bundle, looks next to sys.executable.
+    Otherwise falls back to the system PATH.
+    """
+    if getattr(sys, "frozen", False):
+        # Frozen PyInstaller bundle — ffmpeg is next to the sidecar binary
+        bundle_dir = os.path.dirname(sys.executable)
+        candidates = [
+            os.path.join(bundle_dir, "ffmpeg.exe" if sys.platform == "win32" else "ffmpeg"),
+            os.path.join(bundle_dir, "ffmpeg"),
+        ]
+        for path in candidates:
+            if os.path.isfile(path):
+                return path
+    return "ffmpeg"
+
+
+def get_ffprobe_path() -> str:
+    """Return the path to the ffprobe binary.
+
+    When running as a frozen PyInstaller bundle, looks next to sys.executable.
+    Otherwise falls back to the system PATH.
+    """
+    if getattr(sys, "frozen", False):
+        bundle_dir = os.path.dirname(sys.executable)
+        candidates = [
+            os.path.join(bundle_dir, "ffprobe.exe" if sys.platform == "win32" else "ffprobe"),
+            os.path.join(bundle_dir, "ffprobe"),
+        ]
+        for path in candidates:
+            if os.path.isfile(path):
+                return path
+    return "ffprobe"