Backend:
- Add `files` field to `Message` model so uploaded file metadata survives page refresh
- Pass `files` through websocket handler → `agent.run_stream` / `agent.run`
- `list_tools`: make `profile_id` required; return error instead of all-tools fallback

Webclient:
- Call `fetchFiles()` after successful file upload for immediate Files tab update
- Live refresh file tree on filesystem (write/edit/append/mkdir/rm/cp/mv), terminal, and code_exec tool calls
- Add manual refresh button (desktop) and pull-to-refresh (mobile) to Files tab
- Fix live link updates: move regex creation inside per-message loop to avoid lastIndex state leak
- Restore full profile name text next to avatar in ChatHeader; hide avatar in header
- Fix mobile ArtifactsPanel: collapse tab text labels so close button fits with 3 tabs

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

GnAvatar render function ignores default slot content; it only reads
src, icon, and initials props. Fixes broken user avatar image display.

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

- ProfileBadge.vue: GnBadge → GnAvatar with profile initials
- AppSidebar.vue: custom user-avatar/img → GnAvatar with image or fallback initial
- WelcomeScreen.vue: profile-icon → GnAvatar with Phosphor icon + secondary variant

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

- 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>

- 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>