feat(enroll): strip master API and frontend from agent tarball

Agents never run the FastAPI master app (decnet/web/) or serve the React
frontend (decnet_web/) — they run decnet.agent, decnet.updater, and
decnet.forwarder, none of which import decnet.web. Shipping the master
tree bloats every enrollment payload and needlessly widens the worker's
attack surface.

Excluded paths are unreachable on the worker (all cli.py imports of
decnet.web are inside master-only command bodies that the agent-mode
gate strips). Tests assert neither tree leaks into the tarball.

decnet/web/router/swarm_mgmt/api_enroll_bundle.py

@@ -61,8 +61,12 @@ _EXCLUDES: tuple[str, ...] = (
     "tests", "tests/*",
     "development", "development/*",
     "wiki-checkout", "wiki-checkout/*",
-    "decnet_web/node_modules", "decnet_web/node_modules/*",
-    "decnet_web/src", "decnet_web/src/*",
+    # Frontend is master-only; agents never serve UI.
+    "decnet_web", "decnet_web/*", "decnet_web/**",
+    # Master FastAPI app (API, routers, master-side DB) is not run on agents.
+    # The `agent` / `updater` / `forwarder` commands have their own apps under
+    # decnet/agent, decnet/updater — they don't import decnet.web.
+    "decnet/web", "decnet/web/*", "decnet/web/**",
     "decnet-state.json",
     "master.log", "master.json",
     "decnet.tar",

tests/api/swarm_mgmt/test_enroll_bundle.py

@@ -297,6 +297,11 @@ async def test_get_tgz_contents(client, auth_token, tmp_path):
         assert not bad.endswith(".env"), f"leaked env file: {bad}"
         assert ".env.local" not in bad, f"leaked env file: {bad}"
         assert ".env.example" not in bad, f"leaked env file: {bad}"
+        # Master-only trees: agents don't run the FastAPI master app or the
+        # React frontend, so shipping them bloats the tarball and widens the
+        # worker's attack surface for no benefit.
+        assert not bad.startswith("decnet_web/"), f"leaked frontend: {bad}"
+        assert not bad.startswith("decnet/web/"), f"leaked master-api: {bad}"
 
     # INI content is correct
     ini = tf.extractfile("etc/decnet/decnet.ini").read().decode()