Add speech-to-text feature using Faster Whisper container

Adds a mic button to the terminal UI that captures speech, transcribes
it via a Faster Whisper sidecar container, and injects the text into
the terminal input. Includes settings panel for model selection
(tiny/small/medium), port config, and container lifecycle management.

- stt-container/: Dockerfile + FastAPI server for Whisper transcription
- Rust backend: STT container management, transcribe_audio IPC command
- Frontend: useSTT hook, SttButton, SttSettings, WAV encoder
- CI: Gitea Actions workflow for multi-arch STT image builds

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

app/src-tauri/src/commands/mod.rs

@@ -5,6 +5,7 @@ pub mod help_commands;
 pub mod mcp_commands;
 pub mod project_commands;
 pub mod settings_commands;
+pub mod stt_commands;
 pub mod terminal_commands;
 pub mod update_commands;
 pub mod web_terminal_commands;