security: harden gitignore and add config example files [v1.3.7]

- Expanded .gitignore: root venv, npx_cache, AI metadata (.remember, .claude),
  data/ (SQLite DB), frontend/config/, frontend/public/icons/, certificates,
  docker-compose.override.yml
- Removed backend/config/ldap_config.json from git tracking (contains real IPs/credentials)
- Added backend/config/ldap_config.json.example with placeholder template
- Updated backend/.env.example: added JWT_SECRET_KEY, ALLOWED_ORIGINS, DATA_DIR, LOGS_DIR

VERSION.json

@@ -1,10 +1,10 @@
 {
-  "version": "1.3.6",
-  "last_build": "2026-04-11-1714",
-  "commit": "ccc69d92",
+  "version": "1.3.7",
+  "last_build": "2026-04-11-1936",
+  "commit": "pending",
   "changelog": [
-    "v1.3.5: Security audit complete. JWT Bearer auth (C-01), rate limiting (H-02), CORS config (M-01), and all code comments translated to English (STRICT ENGLISH POLICY)",
-    "v1.3.4: Created USER_GUIDE.md for end-users and integrated into export bundle",
-    "v1.3.3: Added comprehensive project README.md documenting all operational modes"
+    "v1.3.7: Security hardening — expanded .gitignore (venv, caches, ldap configs, AI metadata), removed backend/config/ldap_config.json from git tracking, added ldap_config.json.example and updated .env.example",
+    "v1.3.6: Scanner UI redesign (autonomous OCR, countdown), Item Type datalist, save-version automation",
+    "v1.3.5: Security audit complete. JWT Bearer auth (C-01), rate limiting (H-02), CORS config (M-01), and all code comments translated to English (STRICT ENGLISH POLICY)"
   ]
 }