fix(editor): improve mobile scrolling, highlighting, and keyboard behavior

[bajrangCoder]

Fixes: #2318

[greptile-apps]

Greptile Summary

This PR improves the mobile CodeMirror experience and vendors the supporting CodeMirror changes.

• Adds controlled mobile scrolling with bounded rendering and viewport-priority parsing.
• Adds explicit Android virtual-keyboard handling and caret-reveal behavior.
• Preserves native selection behavior for read-only editor content.
• Bounds restored-file language preparation so a stalled provider cannot block startup.
• Updates vendored CodeMirror sources, generated distributions, patches, packages, tests, and benchmark tooling.

Confidence Score: 5/5

The PR appears safe to merge; both previously reported failures are resolved and no actionable new regression remains.

The restored-file language wait is now bounded without discarding its pending provider, and ambiguous diagonal gestures retain vertical scrolling instead of entering the prior dead zone. Both previous threads are resolved, and the follow-up changes include focused regression coverage.

Important Files Changed

Filename	Overview
src/cm/fileLanguage.ts	Bounds restored-file language preparation while preserving the pending provider for later editor initialization.
vendor/codemirror-view/src/controlled-scroll.ts	Assigns ambiguous diagonal gestures to controlled vertical scrolling while retaining native handling for clearly horizontal swipes.
tests/unit/codemirrorRendering.test.ts	Adds regression coverage for diagonal gesture ownership and controlled scrolling.
tests/unit/fileLanguage.test.ts	Verifies timeout behavior and safe handling of providers that settle after startup proceeds.
package.json	Points CodeMirror dependencies at synchronized vendored packages and adds vendor build and verification commands.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  Touch[Mobile touch gesture] --> Classify{Gesture direction}
  Classify -->|Clearly horizontal| NativePan[Native horizontal pan]
  Classify -->|Vertical or ambiguous| ControlledScroll[Controlled vertical scroll]
  ControlledScroll --> BufferedRender[Bounded viewport rendering]

  Restore[Restore foreground file] --> Preload[Start language provider]
  Preload --> Wait{Settles within 250 ms?}
  Wait -->|Yes| OpenHighlighted[Open with prepared language]
  Wait -->|No| OpenText[Open text without blocking]
  OpenText --> LateLanguage[Reuse pending provider when editor initializes]

  EditAction[Explicit editable focus] --> Focus[Focus editor]
  Focus --> ShowIME[Request Android virtual keyboard]
  ShowIME --> Reveal{User browsing viewport?}
  Reveal -->|No| Caret[Reveal caret]
  Reveal -->|Yes| Preserve[Preserve browsed position]

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_{Reviews (2): Last reviewed commit: "fix(editor): bound startup language wait..." | Re-trigger Greptile}

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