refactor(prober): generalise ActiveProbe registry to absorb Ipv6LeakProbe

ActiveProbe.run/syslog_fields/publish_payload now accept port=None so
non-port-iterating probes can live in the registry. Ipv6LeakProbe replaces
the hand-rolled _ipv6_leak_phase special case in worker.py; it runs last
via priority=999. _probe_cycle no longer has an ad-hoc phase call.

Fixes three stale test files (test_prober_bus, test_prober_rotation,
test_prober_worker) that were broken since the 916b21b6 registry refactor.

decnet/prober/probes/jarm.py

@@ -6,27 +6,29 @@ from decnet.prober.base import ActiveProbe
 from decnet.prober.jarm import JARM_EMPTY_HASH, jarm_hash
 from decnet.telemetry import traced as _traced
 
-DEFAULT_PORTS: list[int] = [443, 8443, 8080, 4443, 50050, 2222, 993, 995, 8888, 9001]
+DEFAULT_PORTS: list[int | None] = [443, 8443, 8080, 4443, 50050, 2222, 993, 995, 8888, 9001]
 
 
 class JarmProbe(ActiveProbe):
     probe_name = "jarm"
-    default_ports = DEFAULT_PORTS
+    default_ports: list[int | None] = DEFAULT_PORTS
     event_type = "jarm_fingerprint"
     rotation_type = "jarm"
     rotation_hash_key = "jarm_hash"
     priority = 100
 
     @_traced("prober.jarm_probe")
-    def run(self, ip: str, port: int, timeout: float) -> dict[str, Any] | None:
+    def run(self, ip: str, port: int | None, timeout: float) -> dict[str, Any] | None:
+        if port is None:
+            return None
         h = jarm_hash(ip, port, timeout=timeout)
         if h == JARM_EMPTY_HASH:
             return None
         return {"jarm_hash": h}
 
-    def syslog_fields(self, ip: str, port: int, result: dict[str, Any]) -> tuple[dict[str, Any], str]:
+    def syslog_fields(self, ip: str, port: int | None, result: dict[str, Any]) -> tuple[dict[str, Any], str]:
         h = result["jarm_hash"]
         return {"jarm_hash": h}, f"JARM {ip}:{port} = {h}"
 
-    def publish_payload(self, ip: str, port: int, result: dict[str, Any]) -> dict[str, Any]:
+    def publish_payload(self, ip: str, port: int | None, result: dict[str, Any]) -> dict[str, Any]:
         return {"attacker_ip": ip, "port": port, "jarm_hash": result["jarm_hash"]}