Add client-side image resize and server-side image token budgeting ...

Client (useFileUpload.js):
- Resize images to max 1024px on longest side via Canvas before upload
- JPEG quality 0.9, preserves EXIF orientation
- Reduces typical phone photos from 8 MB → ~400-900 KB

Server (websocket.py):
- Increase limit to 8 images, 50 MB total payload

Server (agent.py):
- Before adding user message to session.context, estimate how many images
  fit in remaining context (500 tok/img, up to 80% of max_context_tokens)
- Images that don't fit are saved as resized JPEGs to session_files/
- References to saved images are appended to the user message text
  so Navi can view them later via image_view tool
- session.messages keeps ALL images for full UI history

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

Persist uploaded files in messages, live file tree updates, and UI polish ...

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>

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>