feat(validators): add noqa suppression support to security and performance validators

- Add centralized _is_noqa_suppressed() to BaseValidator with normalization
  (accepts both SEC001 and SEC-001 formats for ruff compatibility)
- Wire noqa support into all 21 security and 18 performance check functions
- Add ruff external config for SEC/PERF/MOD/EXC codes in pyproject.toml
- Convert all 280 Python noqa comments to dashless format (ruff-compatible)
- Add site/ to IGNORE_PATTERNS (excludes mkdocs build output)
- Suppress 152 false positive findings (test passwords, seed data, validator
  self-references, Apple Wallet SHA1, etc.)
- Security: 79 errors → 0, 60 warnings → 0
- Performance: 80 warnings → 77 (3 test script suppressions)
- Add proposal doc with noqa inventory and remaining findings recommendations

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/marketplace/services/letzshop/store_sync_service.py

@@ -467,7 +467,7 @@ class LetzshopStoreSyncService:
             .first()
         )
         if existing:
-            store_code = f"{store_code[:16]}_{random.randint(100, 999)}"
+            store_code = f"{store_code[:16]}_{random.randint(100, 999)}"  # noqa: SEC042
 
         # Generate subdomain from slug
         subdomain = letzshop_slug.lower().replace("_", "-")[:30]
@@ -477,7 +477,7 @@ class LetzshopStoreSyncService:
             .first()
         )
         if existing_subdomain:
-            subdomain = f"{subdomain[:26]}-{random.randint(100, 999)}"
+            subdomain = f"{subdomain[:26]}-{random.randint(100, 999)}"  # noqa: SEC042
 
         # Create store data from cache
         address = f"{cache_entry.street or ''} {cache_entry.street_number or ''}".strip()

app/modules/marketplace/services/platform_signup_service.py

@@ -540,7 +540,7 @@ class PlatformSignupService:
 
             logger.info(f"Welcome email sent to {user.email}")
 
-        except Exception as e:  # noqa: EXC-003
+        except Exception as e:  # noqa: EXC003
             # Log error but don't fail signup
             logger.error(f"Failed to send welcome email to {user.email}: {e}")