refactor: rename AceJump to Search, add debounce
- Rename AceJump.tsx → Search.tsx and update component name/props
- Rename aceJumpOpenAtom → searchOpenAtom in atoms.ts
- Rename inlineJumpQueryAtom → aceJumpQueryAtom (this is the actual AceJump feature)
- Update all imports and usages in AppShell.tsx and revision-graph/index.tsx
- Update KeyboardShortcutsHelp descriptions
- Add 150ms debounce to search input to prevent lag while typing
- Update TAT-sjxoqgfa issue title to reference Search instead of AceJump