feat: wire deep-scan port ranges and HTTP probe into scanner

run_scan() accepts DeepScanOptions: user port ranges are validated and appended
to the nmap -p list; when http_probe_enabled, open ports are probed for HTTP
signals before fingerprinting. Defaults (no options) reproduce the standard
scan exactly — probe is never called, port list unchanged.

ha-relevant: yes

backend/tests/test_scan.py

@@ -518,7 +518,7 @@ async def test_run_scan_cancelled_mid_scan_skips_remaining_cidrs(db_session: Asy
 
     call_count = 0
 
-    def nmap_side_effect(target: str):
+    def nmap_side_effect(target: str, port_spec: str | None = None):
         nonlocal call_count
         call_count += 1
         # Signal cancellation after the first CIDR scan completes