Make all user menu items functional

- res.users.action_get() RPC: returns preferences action (form dialog)
- /web/session/account endpoint: returns Odoo.com account URL
- /web/session/logout: clears session, redirects to login (was already done)
- support_url set to odoo.com/help (enables Help menu item)
- notification_type + display_switch_company_menu in session_info
- Image handler: path-style URL parsing for avatars

All user dropdown items now work:
  Help → opens odoo.com/help
  Shortcuts → opens command palette (client-side)
  My Preferences → opens user form dialog
  My Odoo.com Account → opens accounts.odoo.com
  Log out → clears session, redirects to login

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pkg/server/webclient.go

@@ -210,7 +210,9 @@ func (s *Server) buildSessionInfo(sess *Session) map[string]interface{} {
 		"max_file_upload_size": 134217728,
 		"home_action_id":       1,
 		"current_menu":         1,
-		"support_url":          "",
+		"support_url":          "https://www.odoo.com/help",
+		"notification_type":    "email",
+		"display_switch_company_menu": false,
 		"test_mode":            false,
 		"show_effect":          true,
 		"currencies": map[string]interface{}{