feat: multi-keybinding support in settings panel (#9738)

## Summary

Adds VS Code-style multi-keybinding support to the Keybinding settings
panel. Commands can now have multiple keybindings displayed, expanded,
and individually managed.

- Fixes #1088

## Changes

### Store (`keybindingStore.ts`)
- `removeAllKeybindingsForCommand(commandId)` — unsets all bindings for
a command
- `updateSpecificKeybinding(old, new)` — replaces a single binding
without affecting others
- `resetKeybindingForCommand` — updated to restore **all** default
bindings, not just the first
- `isCommandKeybindingModified` — updated to compare full sorted sets of
bindings

### UI (`KeybindingPanel.vue`)
- **Data model**: `keybinding: KeybindingImpl | null` → `keybindings:
KeybindingImpl[]`
- **Multi-binding display**: shows up to 2 combos inline with `, `
separator, then `+ N more` badge
- **Expand/collapse**: click any row with 2+ bindings to expand
individual binding rows; chevron-right icon rotates on expand
- **Per-binding actions**: edit (pencil), reset, trash on each expanded
sub-row
- **Parent row actions**: `+`/trash for 2+ bindings, pencil/reset/trash
for 1, `+`/disabled for 0
- **Edit modes**: `edit` (replace specific binding via
`updateSpecificKeybinding`) and `add` (append via `addUserKeybinding`)
- **Right-click context menu**: Change keybinding, Add new, Reset to
default, Remove keybinding — with proper disabled states and lucide
icons
- **Remove all dialog**: confirmation via `showSmallLayoutDialog` with
`RemoveAllKeybindingsHeader`/`Content` components
- **Reset all dialog**: confirmation via `showConfirmDialog` before
resetting all keybindings to defaults
- **Double-click**: 0 bindings → add, 1 → edit, 2+ → no-op (single click
toggles expand)
- **Consistent alignment**: commands without chevron get `pl-5` padding
to align with those that have it

### Tests (`keybindingStore.test.ts`)
- 7 new tests covering `removeAllKeybindingsForCommand`,
`updateSpecificKeybinding`, multi-binding `isCommandKeybindingModified`,
and multi-binding `resetKeybindingForCommand`

### i18n (`main.json`)
- 11 new keys: removeAllKeybindingsTitle/Message, removeAll,
changeKeybinding, addNewKeybinding, resetToDefault, removeKeybinding,
nMoreKeybindings, resetAllKeybindingsTitle/Message, allKeybindingsReset

### New components
- `RemoveAllKeybindingsHeader.vue` — dialog header
- `RemoveAllKeybindingsContent.vue` — dialog body with Close/Remove all
buttons

## Test plan

- [x] `pnpm typecheck` passes
- [x] `pnpm lint` passes (no new errors)
- [x] `pnpm vitest run src/platform/keybindings/` — 45 tests pass
- [x] CodeRabbit review — 0 findings
- [ ] Manual: open Settings → Keybindings, verify multi-binding commands
(e.g. Delete Selected Items, Zoom In) show multiple combos
- [ ] Manual: click row to expand, verify per-binding actions work
- [ ] Manual: right-click row, verify context menu actions
- [ ] Manual: click trash on 2+ binding command, verify "Remove all"
confirmation dialog
- [ ] Manual: click "Reset All" button, verify confirmation dialog
appears
- [ ] Manual: add/edit/remove individual bindings, verify persistence

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9738-feat-multi-keybinding-support-in-settings-panel-3206d73d365081e9b08bd3cfe21495f1)
by [Unito](https://www.unito.io)

browser_tests/tests/dialog.spec.ts

@@ -328,9 +328,11 @@ test.describe('Settings', () => {
     })
     await newBlankWorkflowRow.click()
 
-    // Click edit button
-    const editKeybindingButton = newBlankWorkflowRow.locator('.pi-pencil')
-    await editKeybindingButton.click()
+    // Click add keybinding button (New Blank Workflow has no default keybinding)
+    const addKeybindingButton = newBlankWorkflowRow.locator(
+      '.icon-\\[lucide--plus\\]'
+    )
+    await addKeybindingButton.click()
 
     // Set new keybinding
     const input = comfyPage.page.getByPlaceholder('Enter your keybind')