What changed?

Replaced the brief CarPlay stub in README.md with comprehensive documentation covering the full feature surface.

New sections added:

• Requirements — iOS 16+, CarPlay hardware/simulator, connected device, Siri authorization
• Interface — Two-tab layout (Channels + Direct Messages), per-row detail (unread badges, last-heard timestamps), disconnected state, Favorites vs. Recent DM sections
• Siri Voice Commands — Expanded table with example phrases and descriptions; limitations callout (200-byte cap, single-recipient-only, emoji/admin message exclusions)
• Incoming Message Announcements — Siri read-back behaviour, 50-message unread backfill at session start
• Live Activity — Dynamic Island/Lock Screen widget contents and lifecycle
• Architecture Notes (For Developers) — File-to-role mapping table for all CarPlay/Intents components; notes on debounced isConnected observer and per-session intent-donation de-duplication

Why did it change?

The CarPlay feature was added without adequate documentation. The previous README section was 13 lines covering only a surface-level feature list and an intent-name table, with no requirements, setup steps, UI description, limitations, or developer guidance.

How is this tested?

Documentation-only change; verified by reading the rendered Markdown.

Screenshots/Videos (when applicable)

N/A

Checklist

• My code adheres to the project's coding and style guidelines.
• I have conducted a self-review of my code.
• I have commented my code, particularly in complex areas.
• I have verified whether these changes require an update to existing documentation or if new documentation is needed, and created an issue in the docs repo if applicable.
• I have tested the change to ensure that it works as intended.