Improve LoginPage design: centered card with brand, hint and clear auth button ...

- Replace GnEmptyState with custom centered login card
- Add brand icon, title and subtitle
- Make 'Sign in with gnexus-auth' button large and full-width
- Show session-check spinner while authStore.init() runs
- Rebuild production dist/

Phase 4.5: Conditional UI rendering by permissions ...

Add usePermission() guards across Vue client pages and components:

- DeviceTable: Reboot button only when devices.control
- ActionScriptsGrid: Run button only when scripts.run
- ScriptTable: Enable/Disable only when scripts.edit
- AreaTreePage: Create area only when areas.manage
- AreaDetailPage: Rename/Assign/Unassign/Remove only when areas.manage
- DeviceDetailPage: Edit/Assign/Reset only when devices.edit; ReSetup only when devices.setup; Reboot only when devices.control; Remove only when devices.delete; Firmware Update only when firmware.upload
- DevicesScanningPage: Add (setup) button only when devices.setup
- ScriptDetailPage: Run only when scripts.run; Assign/Unassign/Enable toggle only when scripts.edit
- ScriptsScopesPage: Enable/Disable only when scripts.edit
- FirmwaresListPage: Refresh Catalog only when firmware.upload

Fix ActionScriptsGrid.spec.js to seed auth store with scripts.run permission.

All 167 tests pass.

Phase 4: Vue client auth store, Bearer token injection, router guards, login page ...

Server:
- AuthControllerTrait now supports both session and Bearer token auth
  (resolves user from Authorization: Bearer header via shserv_sessions)

Vue client:
- Add api/auth.js module for access token management
- Inject Authorization: Bearer header in http.js
- Handle 401 in client.js: clear token + redirect to /auth/login
- New Pinia auth store (stores/auth.js): init, refreshToken, logout, hasPermission
- New usePermission composable
- Router guards: redirect unauthenticated to /login, permission-based route blocking
- New LoginPage.vue with gnexus-auth login button
- AppShell: conditional nav items by permission, user bar with logout
- main.js: initialize auth before mounting app
- MSW mocks: /auth/me, /auth/logout, /auth/refresh
- Fix AppShell.spec.js for Pinia + router setup

All 167 tests pass.

Phase 3: Vue client UI for firmware catalog and device OTA updates

Phase 6: Rename webclient-vue to webclient, match legacy dist structure