Polish menu bar notifications #27

What

The menu bar app sends notifications for finished, failed, and interrupted runs, the Agent going offline and coming back, and low memory, low disk, or a hot GPU. They work, but need polish before sharing.

To Polish

• Wording: one consistent style, always naming the Agent and the project. Done: the title names the Agent, the subtitle the command, and the body the project and time.
• Show the exit code only when a run failed, and nothing for runs ended by Ctrl C or ally stop. Done in fix: no interrupted notice after Ctrl C #132.
• Clicking a notification does something useful, such as opening the panel or copying the command to attach.
• Group or limit bursts, so many quick runs do not flood Notification Center.
• A setting in the panel to turn each kind on or off.
• Check on real machines the ones never seen: the Agent coming back online, and the memory, disk, and GPU warnings.

Where

• Wording and rules live in Rust, in crates/ally-cli/src/watch/. The Swift app only posts what it is given.