feat(cardinal): switch between search input and results panel using arrow keys

[ldm0]

fixes #189

[Copilot]

Pull request overview

Enables seamless keyboard navigation between the search input and the files results list, addressing issue #189 by allowing ArrowDown to enter results (and ArrowUp to return to search) without requiring a mouse click.

Changes:

• Add an onNavigateFromSearchToResults callback in useFilesTabState that triggers when ArrowDown reaches the newest history tail.
• Update App to select the first result + blur the search input when navigating from search → results, and add separate focus helpers (focusSearchInput vs focusAndSelectSearchInput).
• Extend global hotkey handling to return focus to the search input when ArrowUp is pressed on the first result row; update and add tests covering the new navigation flows.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
cardinal/src/hooks/useFilesTabState.ts	Adds optional callback to transition from search input to results when ArrowDown hits history tail.
cardinal/src/hooks/useAppWindowListeners.ts	Renames quick-launch focus handler to focusAndSelectSearchInput and updates effect deps accordingly.
cardinal/src/hooks/useAppHotkeys.ts	Tracks activeRowIndex and adds ArrowUp behavior to move focus back to search from the first result.
cardinal/src/App.tsx	Implements navigation from search → results (select first row + blur input) and introduces separate focus helpers.
cardinal/src/hooks/tests/useFilesTabState.test.ts	Adds unit tests for ArrowDown-to-results behavior at history tail and modifier handling.
cardinal/src/hooks/tests/useAppWindowListeners.test.ts	Updates tests to reflect focusAndSelectSearchInput rename.
cardinal/src/hooks/tests/useAppHotkeys.test.ts	Updates tests for new options and adds coverage for ArrowUp from first result returning focus to search.
cardinal/src/tests/App.searchNavigation.test.tsx	Adds integration-style test asserting ArrowDown from search selects first result and blurs search input.

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