Tri-State Relay Service 2.3.0

• Added a bounded playback boost with output limiting for generated voice audio, making quieter voices easier to hear without changing the app-owned playback safeguards.
• Added the [voice] gain_db TOML setting with validated 0 through 12 dB values and a 6 dB default.
• Added relay config set --playback-gain-db <0-12> for changing playback boost from the CLI, including decimal values.
• Added a compact, auto-saving Playback volume boost slider to Settings > Voice for whole-decibel adjustments.
• Preserved the emergency direct-say fallback without amplification.
• Updated the app and CLI version to 2.3.0.