Fix critical security vulnerabilities in location endpoints

SECURITY FIXES:
- Remove dangerous public DELETE /api/locations/:id endpoint
- Add rate limiting to POST /api/locations (10 requests per 15 minutes)
- Add input validation with length limits (500 chars address, 1000 chars description)
- Add suspicious activity logging for abuse detection
- Install express-rate-limit for protection against spam/DoS

CHANGES:
- Removed LocationDeleteRequest interface (no longer needed)
- Updated tests to expect new security validation behavior
- Added comprehensive tests for length validation
- Fixed test setup issue with undefined constants

Security Impact:
- CRITICAL: Prevents unauthorized deletion of location reports
- HIGH: Prevents spam submissions and DoS attacks
- MEDIUM: Prevents buffer overflow and injection attacks via oversized inputs

All 125 tests passing with new security validations.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

package-lock.json

@@ -13,6 +13,7 @@
         "cors": "^2.8.5",
         "dotenv": "^17.0.1",
         "express": "^4.18.2",
+        "express-rate-limit": "^7.5.1",
         "node-cron": "^3.0.3",
         "sqlite3": "^5.1.6",
         "swagger-jsdoc": "^6.2.8",
@@ -3674,6 +3675,21 @@
         "url": "https://opencollective.com/express"
       }
     },
+    "node_modules/express-rate-limit": {
+      "version": "7.5.1",
+      "resolved": "https://registry.npmjs.org/express-rate-limit/-/express-rate-limit-7.5.1.tgz",
+      "integrity": "sha512-7iN8iPMDzOMHPUYllBEsQdWVB6fPDMPqwjBaFrgr4Jgr/+okjvzAy+UHlYYL/Vs0OsOrMkwS6PJDkFlJwoxUnw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 16"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/express-rate-limit"
+      },
+      "peerDependencies": {
+        "express": ">= 4.11"
+      }
+    },
     "node_modules/fast-json-stable-stringify": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/fast-json-stable-stringify/-/fast-json-stable-stringify-2.1.0.tgz",