Remove all external odoo.com URLs — no phone home

Backend (Go):
- handleSessionAccount: returns /odoo/action-100 (local settings)
- support_url: empty string

Frontend (JS):
- user_menu_items.js: account link navigates locally, no fallback
- upgrade_dialog.js: no external upgrade URL
- documentation_link.js: returns empty string

All 5 identified external URL references eliminated.

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

pkg/server/webclient.go

@@ -211,7 +211,7 @@ func (s *Server) buildSessionInfo(sess *Session) map[string]interface{} {
 		"max_file_upload_size": 134217728,
 		"home_action_id":       1,
 		"current_menu":         1,
-		"support_url":          "https://www.odoo.com/help",
+		"support_url":          "",
 		"notification_type":    "email",
 		"display_switch_company_menu": false,
 		"test_mode":            false,