feat(ui): add gg / G navigation in hunk diff

[SalzDevs]

Summary

• add Vim-style navigation aliases to Hunk review controls:
  • G jumps to bottom (alias for End)
  • gg jumps to top (alias for Home)
• support the aliases in both full app mode and pager mode
• reset pending g state when entering menus/help/filter so gg stays predictable
• update controls help copy to include the new aliases
• add interaction coverage for G -> bottom and gg -> top behavior

Testing

• bun run format:check
• bun run typecheck
• bun run lint
• bun test src/ui/AppHost.interactions.test.tsx src/ui/components/ui-components.test.tsx

Closes #286

[greptile-apps]

Greptile Summary

This PR adds Vim-style gg (jump to top) and G (jump to bottom) navigation aliases to the diff viewer, implemented as a single-key state machine (pendingTopJumpRef) that is shared across both full-app and pager keyboard handlers. The pending state is correctly reset whenever a menu, help dialog, or filter intercepts a key.

• resolveJumpShortcut is introduced as a shared helper called at the top of both handleAppShortcut and handlePagerShortcut; it mutates a ref to track the first g keystroke.
• HelpDialog and the snapshot test are updated to surface the new aliases in the controls reference.
• A new interaction test verifies G→bottom and gg→top sequencing in full-app mode, but the pager-mode code path added in the same PR has no dedicated test coverage.

Confidence Score: 4/5

Safe to merge; the shortcut logic is sound and the state machine correctly resets across all handled modes and overlay states.

The implementation is correct end-to-end for the full-app path and the modifier-guard inconsistency in isUppercaseGKey is unlikely to cause a real issue on standard terminals. The pager-mode path is untested but mirrors the app-mode path exactly, so a silent regression there is low-probability rather than guaranteed.

src/ui/hooks/useAppKeyboardShortcuts.ts — the isUppercaseGKey modifier guard inconsistency is worth a second look before shipping.

Important Files Changed

Filename	Overview
src/ui/hooks/useAppKeyboardShortcuts.ts	Core implementation of gg/G shortcuts via a ref-based state machine; logic is correct but isUppercaseGKey's sequence branch skips modifier guards that the rest of the file applies consistently.
src/ui/AppHost.interactions.test.tsx	Adds integration test covering G→bottom and gg→top in full-app mode; pager-mode path (also changed) has no corresponding test.
src/ui/components/chrome/HelpDialog.tsx	Adds gg/G row to the keyboard shortcuts table in the help dialog; straightforward documentation-only change.
src/ui/components/ui-components.test.tsx	Snapshot updated to include the new gg/G help line; no logic concerns.
CHANGELOG.md	Changelog entry added for gg/G aliases under the Unreleased section; no issues.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    K[KeyEvent received] --> MT{handleMenuToggleShortcut?}
    MT -->|yes| RESET_MT[reset pendingTopJumpRef\nreturn]
    MT -->|no| PM{pagerMode?}
    PM -->|yes| PH[handlePagerShortcut]
    PM -->|no| HS{handleHelpShortcut?}
    HS -->|yes| RESET_H[reset pendingTopJumpRef\nreturn]
    HS -->|no| MS{handleMenuShortcut?}
    MS -->|yes| RESET_M[reset pendingTopJumpRef\nreturn]
    MS -->|no| FS{handleFilterShortcut?}
    FS -->|yes| RESET_F[reset pendingTopJumpRef\nreturn]
    FS -->|no| AH[handleAppShortcut]
    PH --> RJ1[resolveJumpShortcut]
    AH --> RJ2[resolveJumpShortcut]
    RJ1 --> GU1{isUppercaseGKey?}
    RJ2 --> GU1
    GU1 -->|yes| BOT[return bottom\nscrollDiff +1 content]
    GU1 -->|no| GL1{isLowercaseGKey?}
    GL1 -->|no| CLR[clear pending\nreturn null → other shortcut]
    GL1 -->|yes| PEND{pending already?}
    PEND -->|yes| TOP[return top\nscrollDiff -1 content]
    PEND -->|no| SET[set pending = true\nreturn pending → no-op]

Loading

Prompt To Fix All With AI

Fix the following 2 code review issues. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 2
src/ui/hooks/useAppKeyboardShortcuts.ts:34-38
**Modifier guards missing on `sequence === "G"` branch**

`isLowercaseGKey` explicitly checks `!key.option && !key.ctrl && !key.meta`, and the second branch of `isUppercaseGKey` does the same. The first branch (`key.sequence === "G"`) skips all four modifier guards entirely — so a combo that happens to produce the raw sequence `"G"` (e.g. on an unusual terminal mapping) would still fire jump-to-bottom. The inconsistency also makes the intent harder to follow at a glance.

```suggestion
function isUppercaseGKey(key: KeyEvent) {
  return (
    (key.sequence === "G" && !key.option && !key.ctrl && !key.meta) ||
    (key.name === "g" && key.shift && !key.option && !key.ctrl && !key.meta)
  );
}
```

### Issue 2 of 2
src/ui/AppHost.interactions.test.tsx:1693-1763
**Pager-mode path not exercised**

The PR description explicitly states "support the aliases in both full app mode and pager mode", but the new test only exercises `handleAppShortcut` (full app mode). `handlePagerShortcut` has its own independent call to `resolveJumpShortcut`, and there is no test that launches with `pagerMode: true` and verifies `G` → bottom / `gg` → top. A regression in the pager branch would not be caught by the current test suite.

_{Reviews (1): Last reviewed commit: "feat(ui): add gg and G navigation shortc..." | Re-trigger Greptile}