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/ipc/handlers.py

@@ -260,10 +260,12 @@ def make_ai_chat_handler() -> HandlerFunc:
                     model=config.get("model", "claude-sonnet-4-6"),
                 ))
             elif provider_name == "litellm":
-                from voice_to_notes.providers.litellm_provider import LiteLLMProvider
+                from voice_to_notes.providers.litellm_provider import OpenAICompatibleProvider
 
-                service.register_provider("litellm", LiteLLMProvider(
+                service.register_provider("litellm", OpenAICompatibleProvider(
                     model=config.get("model", "gpt-4o-mini"),
+                    api_key=config.get("api_key"),
+                    api_base=config.get("api_base"),
                 ))
             return IPCMessage(
                 id=msg.id,