feat(cmp): vendor-agnostic consent data model — 13 new fields

Extend banner consent records with consent_method, banner_version,
banner_config_hash, geo, page_url, referrer, device info, session_id
and consent_scope for full Art. 7 DSGVO proof with any tracking vendor.

Migration 107, backward-compatible (all fields nullable).
Admin detail modal shows tracking context, device info and technical data.
Fix pre-existing str|None → Optional[str] for Python 3.9 compat.

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

backend-compliance/compliance/api/banner_routes.py

@@ -77,6 +77,15 @@ async def record_consent(
             ip_address=body.ip_address,
             user_agent=body.user_agent,
             consent_string=body.consent_string,
+            consent_method=body.consent_method,
+            page_url=body.page_url,
+            referrer=body.referrer,
+            device_type=body.device_type,
+            browser=body.browser,
+            os=body.os,
+            screen_resolution=body.screen_resolution,
+            session_id=body.session_id,
+            consent_scope=body.consent_scope,
         )
 
 
@@ -206,7 +215,7 @@ async def get_site_stats(
 
 @router.get("/admin/consents")
 async def list_banner_consents(
-    site_id: str | None = None,
+    site_id: Optional[str] = None,
     limit: int = 50,
     offset: int = 0,
     tenant_id: str = Depends(_get_tenant),