feat: implement API versioning /api/v1/

- All backend routers moved to /api/v1/ prefix
- Frontend BASE_URL updated to /api/v1
- Setup redirect middleware updated to redirect to /api/v1/setup
- Health router path fixed: prefix=/api/v1/health, @router.get('')
- conftest.py: set server_status=online for test fixture
- Created Docs/API_VERSIONING.md with deprecation policy
- Updated Docs/Backend-Development.md with versioning section
- Updated Instructions.md curl examples

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Docs/TROUBLESHOOTING.md

@@ -86,6 +86,54 @@ ps aux | grep <pid>
 
 ---
 
+## Rate Limiting
+
+### Getting 429 Too Many Requests
+
+**Symptom:** API returns HTTP 429 with `rate_limit_exceeded` error code.
+
+**Cause:** You have exceeded the per-IP rate limit for a specific operation.
+
+**Diagnosis:**
+1. Check the `Retry-After` header in the response — this tells you how many seconds to wait
+2. Look for the log event `*_rate_limit_exceeded` which shows the bucket and client IP
+
+**Rate limit buckets:**
+| Bucket | Limit | Window | Operations |
+|--------|-------|--------|------------|
+| `bans:ban` | 100 | 1 minute | Ban IP addresses |
+| `bans:unban` | 100 | 1 minute | Unban IP addresses |
+| `blocklist:import` | 10 | 1 hour | Import blocklists |
+| `config:update` | 50 | 1 minute | Update configuration |
+| `jail:update` | 100 | 1 minute | Update jail config |
+| `jail:create` | 100 | 1 minute | Add log paths, assign filters/actions |
+| `jail:delete` | 100 | 1 minute | Remove log paths, actions |
+| `jail:activate` | 100 | 1 minute | Activate jails |
+| `jail:deactivate` | 100 | 1 minute | Deactivate jails |
+| `filter:update` | 50 | 1 minute | Update filters |
+| `filter:create` | 50 | 1 minute | Create filters |
+| `filter:delete` | 50 | 1 minute | Delete filters |
+| `action:update` | 50 | 1 minute | Update actions |
+| `action:create` | 50 | 1 minute | Create actions |
+| `action:delete` | 50 | 1 minute | Delete actions |
+
+**Solution:**
+1. Wait for the `Retry-After` period before retrying
+2. If you hit the limit during legitimate bulk operations, consider batching requests
+3. For blocklist imports (10/hour), ensure automated imports are not more frequent
+
+**Prevention:**
+- Monitor `*_rate_limit_exceeded` log events
+- Adjust limits via environment variables if needed (see `Docs/CONFIGURATION.md`)
+- For bulk operations, implement client-side throttling
+
+**Note:** If rate limiting triggers unexpectedly for legitimate use, check for:
+- Internal monitoring scripts hitting endpoints too frequently
+- Multiple users behind the same proxy IP
+- Stale rate limit state after process restart (uses in-memory tracking)
+
+---
+
 ## General Recovery Commands
 
 Clear all locks: