Bump version to 0.2.6 in Cargo.toml and Cargo.lock.

Add audio management with embedded and user-defined sounds

- Introduce `audio.rs` to manage sound playback, caching, and volume control for microphone on/off transitions.
- Embed default sounds and provide fallback mechanisms using system tools (`paplay`, `canberra-gtk-play`) for sound effects.
- Add `config.rs` updates to support sound settings (on/off, volume, custom files) via CLI and persisted configuration.
- Define constants to handle defaults for embedded sound effects and improved key mapping using macros.

Refactor system service and configuration workflow to align with new sound management functionality.

Add audio management with embedded and user-defined sounds

- Introduce `audio.rs` to manage sound playback, caching, and volume control for microphone on/off transitions.
- Embed default sounds and provide fallback mechanisms using system tools (`paplay`, `canberra-gtk-play`) for sound effects.
- Add `config.rs` updates to support sound settings (on/off, volume, custom files) via CLI and persisted configuration.
- Define constants to handle defaults for embedded sound effects and improved key mapping using macros.

Refactor system service and configuration workflow to align with new sound management functionality.

Add config file support with auto-creation and CLI updates

- Introduce `~/.config/pttkey/config.toml` for persistent configuration with automatic creation and CLI option integration.
- Enhance CLI with `--reverse` and `--no-reverse` options to toggle mute behavior.
- Embed default sound files (`mute.wav`, `unmute.wav`) with fallback mechanisms for audio playback.
- Update systemd service and install script to reflect config file usage.
- Add Serde and TOML dependencies to handle configuration serialization.

Bump version to match new functionality.

Bump version to 0.2.2 and update release workflow to include addition…

…al artifacts. Modify install script to handle prebuilt binaries.

Bump version to 0.2.1 in Cargo.toml for release.

Add system dependencies installation step to CI and release workflows