fix(dashboard): UI polish — modals, layout, consistency, test fixes

Dashboard UX polish pass — consolidates create forms into modals
triggered from the page header, fixes layout inconsistencies, adds
scroll-to navigation for the Keys page, and aligns the TokenBar with
the design system.

Changes:
- App.tsx: add padding to sidebar header
- resolve-page-title.ts: add missing routes, better fallback title
- en.ts: fix nav labels (Profiles was 'profiles : multi agents')
- ModelsPage: two-col layout, auxiliary tasks modal, TokenBar redesign
- ProfilesPage: create button in header, form in modal, Checkbox component
- CronPage: create button in header, form in modal
- EnvPage: scroll-to sub-nav in header, fix text overflow

Modal and dialog standardization:
- Replace all native confirm()/window.confirm() with ConfirmDialog
  (OAuthProvidersCard, PluginsPage, ModelsPage, ConfigPage)
- Add useModalBehavior hook (Escape-to-close, scroll lock, focus restore)
- Apply hook to ProfilesPage, CronPage, AuxiliaryTasksModal

Component fixes (from PR review):
- Checkbox: fix controlled/uncontrolled mismatch, add focus-visible ring
- TokenBar: add rounded-full to legend dots, remove dead code

CI/test fixes:
- Fix TS unused imports (noUnusedLocals), type-narrow PickerTarget union
- Add windows-footgun suppression on platform-guarded os.killpg
- Fix 19 stale unit tests + 9 e2e tests broken by recent main changes
- Restore minimal example-dashboard plugin for plugin auth test

plugins/example-dashboard/dashboard/manifest.json

@@ -0,0 +1,14 @@
+{
+  "name": "example",
+  "label": "Example",
+  "description": "Example dashboard plugin — used by test suite for auth coverage",
+  "icon": "Sparkles",
+  "version": "1.0.0",
+  "tab": {
+    "path": "/example",
+    "position": "after:skills"
+  },
+  "slots": [],
+  "entry": "dist/index.js",
+  "api": "plugin_api.py"
+}