webclient: refresh vendored gnexus-ui-kit to v1.0.0 + dist-css wiring ...

- vendor 0.2.0 (snapshot d640a9e, ~93M with demo/node_modules) replaced
  with a clean 1.0.0 subset (4.5M): src/{js,scss,vue}, dist/{css,vue,js},
  dist assets (IBM Plex Mono fonts), docs, README/CLAUDE/AGENTS
- kit component CSS now consumed as prebuilt dist (import
  'gnexus-ui-kit/css' before app styles): kit 1.0 _fonts.scss uses
  relative url() for IBM Plex Mono, which breaks source compilation;
  the bundler resolves them into vendor dist/assets
- main.scss drops @use 'kit' as * (still broken by the font urls);
  kit-deps stays for focus_ring + SCSS tokens in app.scss and scoped
  blocks
- app.scss scrollbar block removed (kit.css 1.0 ships identical styles)
- vite.config: dead @kit alias removed; brand-new 'gnexus-ui-kit/css'
  alias now consumed
- product dist/ rebuilt (tracked: served by backend, deployed from git)

Verified: vitest 111 passed, vite build OK (ttf emitted, hashed),
preview screenshot renders dark kit theme with new density

PWA: installable webclient, offline shell, web push ...

Installability:
- public/manifest.webmanifest (standalone, theme #16161E) + PNG icons
  generated from logo.svg (regular + maskable, served via /images mount)
- index.html: manifest link, theme-color, apple-touch-icon

Offline shell:
- hand-rolled sw.js (no workbox): navigation = network-first (3s race)
  with cached-shell fallback + background refresh (a stale cached shell
  would 404 on entry chunks after a deploy); /assets/* cache-first
  (content-hashed); /images/* cache-first capped; /api,/ws,/auth,/push,
  /content pass-through
- vite closeBundle plugin stamps __NAVI_BUILD_VERSION__ (digest of
  index.html + asset names) into dist/sw.js; sw.js served no-store so
  every deploy reactivates the SW and activation evicts old caches
- SW registration in main.js, PROD only (dev HMR untouched)
- OfflineBanner (useOnline composable) over the app shell

Web push (VAPID, pywebpush):
- navi/push/ package: push_subscriptions table (postgres, boot-time DDL),
  PushSubscriptionStore, PushService (async fan-out, to_thread sends,
  404/410 prunes dead endpoints, per-session cooldown)
- routes: GET /push/vapid-key, POST/DELETE /push/subscribe (auth-gated)
- trigger in orchestrator run_agent + run_recall: push on StreamEnd when
  no WebSocket client watches the session; fire-and-forget, never
  disturbs the run; anonymous fallback only when auth is off
- client: usePush composable + Notifications settings panel (enable/
  disable via PushManager.subscribe with the server VAPID key)
- notification click focuses the app at /#<session_id> (hash routing
  opens the right chat); payload body is a markdown-stripped <=140-char
  preview

NAVIVAPID keys empty = push fully disabled (graceful, like other optional
integrations). dist/ artifacts committed per repo convention.

Tests: pytest push store/service/routes/trigger (+23), vitest usePush
(83 webclient tests green). Full suite 1143 passed.

port: 8000/8001 -> 8099/8098 everywhere ...

navi runs on shared servers where 8000/8001 are usually taken. New
defaults: API 8099, navi_ui MCP 8098. Touched: config defaults
(navi_port, navi_ui_mcp_port, public_url, gnauth_redirect_uri),
navi-server launcher docs, env.template/.env.example, install.sh
health-check fallback, terminal client base_url, webclient dev configs
(useWebSocket, contentLinks, vite proxy), android url hint, docs.
Also made the navi_ui FastMCP constructor port settings-driven instead
of a hardcoded 8001 (it was overridden at start anyway).

Wire gnexus-ui-kit v0.2.0 Vue 3 adapter and migrate Wave 1 components. ...

- Update vendor/gnexus-ui-kit to v0.2.0 (Vue components + composables)
- Add Vite aliases for gnexus-ui-kit/vue and gnexus-ui-kit/css
- Install GnexusUiVue plugin in main.js + GnToastProvider in App.vue
- Migrate ProfileBadge → GnBadge
- Migrate ErrorMessage → GnAlert
- Migrate ConfirmDialog → GnConfirmDialog
- Migrate raw <button> elements → GnButton / GnIconButton in:
  WelcomeScreen, LoginScreen, ChatArea, ChatHeader, AppSidebar,
  ArtifactsPanel, UserMessage, AssistantMessage, SelectionToolbar

Build and tests pass (51/51).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Migrate to Vue webclient; rename old client to old_webclient ...

- client/ → old_webclient/ (vanilla JS client preserved as reference)
- webclient/ — new Vue 3 + Pinia webclient (source + dist build)
- vite.config.js: outDir changed to webclient/dist/
- main.py: serve /assets and /images from webclient/dist/,
  index.html from webclient/dist/index.html
- .gitignore: exclude webclient/node_modules/, include webclient/dist/

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>