fix(shortcuts): keep global shortcuts live inside CodeMirror

[Chloe-JY]

Problem

⌘W does not close the active tab while the CodeMirror editor has focus. The close handler lives in a capture-phase document keydown listener, so CodeMirror never even sees the event — the bug is upstream inside the handler: the workstation-route ⌘G/⌘E/⌘J block does a bare return when the event target is editable, and isEditableElementExtended explicitly matches .cm-editor/.cm-content. With editor focus the handler aborts before the case "w" branch — and also silently kills ⌘1/⌘2/⌘3 station switch, ⌘N, ⌘T, ⌘,, ⌘P, and zoom.

The editable guard itself is legitimate (⌘G is find-next in CM's searchKeymap); it was just scoped to the whole handler instead of the three chords it protects.

Solution

• New pure resolver workstationEditorToolShortcut.ts (same extraction pattern as digitZeroShortcut): claims only ⌘G/⌘E/⌘J, returns null for them while an editable surface has focus, and never claims any other key. The handler dispatches on the resolver result and falls through on null, so ⌘W reaches handleCloseCurrentTab → closeActiveWorkStationTabAtom with editor focus. ⌘G/⌘E/⌘J behavior while typing is unchanged.
• case "/" now yields to CodeMirror (.cm-editor target): the buggy early-return was accidentally protecting CM's ⌘/ toggle-comment (defaultKeymap Mod-/), and without this guard the fix would have hijacked it into the model selector.

Potential risks

• Previously-dead shortcuts now work with editor focus: ⌘1/⌘2/⌘3, ⌘N, ⌘P, ⇧⌘F search sidebar, ⇧⌘M maximize (the last shadows CM's rarely-used lint-panel binding). This matches how these shortcuts already behave in every other editable surface (e.g. chat input on non-workstation routes). ⌘A, ⌘F, and ⌘K keep their existing per-case editable guards.
• The full keydown handler is not unit-testable in this node-env vitest suite (hence the pure-resolver extraction); the handler restructuring itself is covered by typecheck + review only. No E2E was run and the change was not exercised in the running Tauri app.
• Keyboard-only change, nothing visual — no screenshots.

Verification

Verified in a detached worktree at origin/develop (57c8ffd) containing only this PR's three files (node_modules symlinked):

• npx tsc --noEmit --pretty false -p tsconfig.json — exit 0
• npx vitest run --config config/vitest.config.ts src/hooks/navigation/useGlobalShortcuts/__tests__/workstationEditorToolShortcut.test.ts — 3 tests pass, including the regression contract ("never claims foreign keys, regardless of focus")
• npx eslint over all three files — clean

Not run: E2E; manual ⌘W check in the running app. The commit was built with git plumbing from a live shared checkout, so git hooks did not run and the Pre-commit hook ran. trailer is absent — typecheck/lint/tests above were run manually instead.