fix(app): prioritize shortcuts in terminal

[Brendonovich]

Summary

• dispatch app shortcuts during keyboard capture so focused terminals cannot swallow them
• support contextual shortcut collisions while preserving global fallbacks
• close the active terminal with Mod+W when terminal input is focused
• collapse the terminal pane after closing its final tab

Validation

• bun typecheck in packages/app
• bun test --preload ./happydom.ts ./src/context/command.test.ts ./src/context/command-keybind.test.ts ./src/context/terminal.test.ts
• repository pre-push typecheck