feat(pro): generalize pro tier to multi-surface extension points

Move the pro mount decnet/services/pro/ -> decnet/pro/ so the Professional tier
can contribute to more than honeypots. The core wires each surface only when
decnet/pro/ is present (absence stays the entitlement gate):

* services  — registry scans decnet/pro/services/ (was decnet/services/pro/)
* API routes — decnet/pro/routes.py exposes ROUTERS, mounted under /api/v1
* web pages  — Vite aliases @pro to the pro frontend (community -> empty stub),
               App.tsx maps proRoutes into <Route>s, Layout renders a
               PROFESSIONAL nav group; both tree-shake out of the community build

Frontend gate mirrors the existing VITE_DECNET_DEVELOPER tree-shake pattern.
Tests: registry + router seams (backend), empty-stub contract (frontend).

decnet/services/registry.py

@@ -6,11 +6,11 @@ Auto-discovers all BaseService subclasses by importing every module in the
 services package. Adding a new service requires nothing beyond dropping a
 new .py file here that subclasses BaseService.
 
-Professional-tier honeypots live in the optional ``decnet.services.pro``
-subpackage, which ships only in the Professional build (a private tree merged
-in at packaging time) and is absent from the open-core Community build. The
-registry scans it when present, so absence of the directory IS the entitlement
-gate — no licence check, no feature flag.
+Professional-tier honeypots live in the optional ``decnet.pro.services``
+subpackage (a clone of the private decnet-professional repo, mounted at
+``decnet/pro/`` and absent from the open-core Community build). The registry
+scans it when present, so absence of the directory IS the entitlement gate —
+no licence check, no feature flag.
 """
 
 import importlib
@@ -40,12 +40,13 @@ def _load_plugins() -> None:
             continue
         importlib.import_module(f"decnet.services.{module_info.name}")
     # Professional build only: present == entitled. Community build has no pro/.
-    pro_dir = package_dir / "pro"
+    pro_dir = package_dir.parent / "pro" / "services"
     if pro_dir.is_dir():
         for mi in pkgutil.iter_modules([str(pro_dir)]):
-            importlib.import_module(f"decnet.services.pro.{mi.name}")
+            importlib.import_module(f"decnet.pro.services.{mi.name}")
     for cls in _all_subclasses(BaseService):
-        if not cls.__module__.startswith("decnet.services."):
+        mod = cls.__module__
+        if not (mod.startswith("decnet.services.") or mod.startswith("decnet.pro.")):
             continue
         instance = cls()  # type: ignore[abstract]
         _registry[instance.name] = instance