Add per-app enable and disable controls

[FuJacob]

What does this PR do?

Briefly describe the changes.

• Adds a persisted per-app disabled blocklist keyed by bundle identifier, with display names stored only for Settings UI metadata.
• Adds menu-bar controls for Enable Globally and Enable in {AppName}, plus a Settings Disabled Apps list with live app icons and remove actions.
• Routes per-app disabled state through the central suggestion availability evaluator so generation, overlays, and Tab acceptance all respect the same policy.

Why is this necessary?

Explain the problem you are solving.

• Users need to disable Tabby in specific apps without turning autocomplete off globally.
• The root issue was that the existing gate only understood global enablement, permissions, and focus support, so app-specific preferences had no single reliable enforcement point.
• Closes Add per-app enable/disable controls #1.

Validation:

• xcodebuild build-for-testing -scheme tabby -destination 'platform=macOS,arch=arm64' passed.
• Full xcodebuild test is still blocked locally by the XCTest bundle signing mismatch between the host app and test bundle.

[Jam-Cai]

Also handle the linting errors before merging