fix(gtm): Fix white screen and implement URL persistence v2.6.1

- Fixed TypeError in SessionBrowser by adding defensive checks for the sessions array.
- Implemented mandatory URL persistence: The research URL is now saved in DB, shown in UI, and included in reports.
- Added 'Start New Analysis' button to the session browser for better UX flow.
- Updated documentation to reflect v2.6.1 changes.

gtm_architect_orchestrator.py

@@ -282,6 +282,13 @@ def phase1(payload):
 
         try:
             specs_data = json.loads(specs_response)
+            
+            # FORCE URL PERSISTENCE: If input was a URL, ensure it's in the metadata
+            if product_input.strip().startswith('http'):
+                if 'metadata' not in specs_data:
+                    specs_data['metadata'] = {}
+                specs_data['metadata']['manufacturer_url'] = product_input.strip()
+            
             data['specs'] = specs_data
         except json.JSONDecodeError:
             logging.error(f"Failed to decode JSON from Gemini response in phase1 (specs): {specs_response}")