feat: Major WhatsApp integration update with Odoo and pause/resume

## Frontend
- Add media display (images, audio, video, docs) in Inbox
- Add pause/resume functionality for WhatsApp accounts
- Fix media URLs to use nginx proxy (relative URLs)

## API Gateway
- Add /accounts/:id/pause and /accounts/:id/resume endpoints
- Fix media URL handling for browser access

## WhatsApp Core
- Add pauseSession() - disconnect without logout
- Add resumeSession() - reconnect using saved credentials
- Add media download and storage for incoming messages
- Serve media files via /media/ static route

## Odoo Module (odoo_whatsapp_hub)
- Add Chat Hub interface with DOLLARS theme (dark, 3-column layout)
- Add WhatsApp/DRRR theme switcher for chat view
- Add "ABRIR CHAT" button in conversation form
- Add send_message_from_chat() method
- Add security/ir.model.access.csv
- Fix CSS scoping to avoid breaking Odoo UI
- Update webhook to handle message events properly

## Documentation
- Add docs/CONTEXTO_DESARROLLO.md with complete project context

## Infrastructure
- Add whatsapp_media Docker volume
- Configure nginx proxy for /media/ route
- Update .gitignore to track src/sessions/ source files

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitignore

@@ -105,12 +105,13 @@ docker-compose.override.yml
 # -----------------------------------------------------------------------------
 # Sessions / Data
 # -----------------------------------------------------------------------------
-sessions/
+/sessions/
 *.session
 *.session.json
 
-# WhatsApp Baileys sessions
+# WhatsApp Baileys sessions (data, not source code)
 services/whatsapp-core/sessions/
+!services/whatsapp-core/src/sessions/
 auth_info*/
 
 # -----------------------------------------------------------------------------