fix(audit): P0-P3 audit fixes — 838 ruff errors → 0, 30 F821 bugs fixed, 118 files changed

- P0: hooks.py 3-tuple fix, trigger_dispatcher Contract, contacts/plugin unregister_actions_by_owner
- P0: 5 test files — check_permission mocks removed, hardcoded DB credential → env var
- P1: attachment_service DmsFile via Contract helper, restore_registry/history_hooks dedup
- P1: mail/plugin restore unregister, mcp_client datetime.now(UTC), saved_views/filters patterns
- P1: ProtectedRoute fail-closed, 13 test assertion fixes (bcrypt, DB-URLs, SECRET_KEYs)
- P2: deprecated notifications → post_system_message (3 files), forgejo Base, report_generator lazy import
- P2: webhooks permissions, deps.py/roles.py plugin perms removed, import_export default
- P2: address/tags/entity_links patterns removed, worker.py Contract-Umgehungen fixed
- P2: 28 frontend TODOs (hardcoded constants, deprecated notification API)
- P3: dead code, duplicates, deprecated imports, private attr, __import__ inline
- P3: 8 frontend TODOs (LucideIcons, inline styles, XSS, i18n)
- ruff: 838 → 0 (612 auto-fix + 246 manual + 27 F821 regression fix)
- F821: 30 → 0 (AutomationDefinition, DmsFile, user_id, Path, Any, String)
- Contract-Umgehungen: 2 neue gefunden (worker.py:169, worker.py:280) und gefixt

app/services/import_export_service.py

@@ -1,5 +1,12 @@
 """Import/export service — CSV/JSON/XLSX import with dry-run preview, partial-failure, CSV/XLSX export.
 
+This service is Contact-specific — it handles import/export for Contacts and
+Companies (both use the Contact model). It is NOT a generic import/export
+service. If other entity types need import/export in the future, a separate
+service or a plugin-based interface should be created.
+
+Declared as Contact-specific (P1-23 fix): no pretense of being generic.
+
 Uses shared helpers from import_export_helpers.py for parsing, writing, mapping,
 and validation.  Implements partial-failure semantics: valid rows are committed
 while invalid rows are collected into a structured error report.