feat(audit): harden API audit log redaction and schema

- Change query_json column from TEXT to JSON, ip/user_agent to CHAR(64)
  for PII redaction compliance
- Update repository, service, and views for hardened schema
- Add architecture contract test for security logging redaction
- Add search resource provider test coverage
- Include DB migration script for existing installs

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

i18n/default_de.json

@@ -1010,6 +1010,7 @@
   "Request details": "Request-Details",
   "Scope": "Geltungsbereich",
   "Query": "Query",
+  "Query metadata (keys)": "Query-Metadaten (Schlüssel)",
   "User agent": "User-Agent",
   "All methods": "Alle Methoden",
   "Tenant ID": "Mandanten-ID",

i18n/default_en.json

@@ -1010,6 +1010,7 @@
   "Request details": "Request details",
   "Scope": "Scope",
   "Query": "Query",
+  "Query metadata (keys)": "Query metadata (keys)",
   "User agent": "User agent",
   "All methods": "All methods",
   "Tenant ID": "Tenant ID",