[hlolli]

Cmd+F on macOS and Ctrl+F on Windows/Linux now open Find and Replace in the focused CodeMirror editor. The panel supports regex, case matching, whole words, and undoable replacement. It also works in tool panes, with replacement hidden for read-only output. Browser Find still works outside editors.

Restore the omitted shortcuts for next/previous match, selecting repeated text, go-to-line, code folding, error navigation, and deleting an empty bracket pair. Style the panels with the current theme and list the shortcuts in the help dialog and guide.

Validation:

• The browser regression failed before the fix. It now passes for macOS, Windows, and Linux keybindings in Chromium, covering focus, regex replacement, Undo, read-only output, folding, errors, and a narrow viewport in light/dark themes. Added it to local E2E CI.
• 1,359 unit tests passed; 59 optional tests skipped.
• Lint, typecheck, formatting, and the full production build passed.

[Copilot]

🟢 Approval recommended

The focused CodeMirror integration has regression coverage and no identified blocking issues; tests were not rerun here.

No open issues 🎉

What changed in this PR

Restores focused-editor Find and Replace and missing CodeMirror editing shortcuts across source editors and tool panes.

Changes:

• Adds shared search support and restores editing, folding, and diagnostic shortcuts.
• Styles editor panels and documents available shortcuts.
• Adds cross-platform browser regression coverage to local CI.

File	Description
src/​styles/​code-mirror-theme.ts	Themes panels, controls, and search highlights.
src/​components/​site-documents/​keyboard-shortcuts.tsx	Lists restored shortcuts in help.
src/​components/​score-tools/​code-pane.tsx	Enables search and multiple selections.
src/​components/​hot-keys/​default-bindings.ts	Removes an obsolete commented binding.
src/​components/​editor/​search.ts	Defines shared search extensions.
src/​components/​editor/​editor.tsx	Integrates search and restored keymaps.
puppeteer-tests/​tests/​editor-find.js	Tests search and editing shortcuts across platforms.
puppeteer-tests/​fixtures/​editor-find.tsx	Provides real editor components for regression tests.
puppeteer-tests/​fixtures/​editor-find.html	Hosts the responsive test fixture.
package.json	Declares the CodeMirror search dependency.
package-lock.json	Records the direct search dependency.
docs/​guide/​reference/​shortcuts.md	Documents search behavior and editing shortcuts.
.github/​workflows/​e2e-local.yml	Adds the regression test to local CI.

_{Review effort: Balanced}