feat(swarm): add decnet swarm deckies to list deployed shards by host

`swarm list` only shows enrolled workers — there was no way to see which
deckies are running and where. Adds GET /swarm/deckies on the controller
(joins DeckyShard with SwarmHost for name/address/status) plus the CLI
wrapper with --host / --state filters and --json.

decnet/web/router/swarm/__init__.py

@@ -15,6 +15,7 @@ from .api_deploy_swarm import router as deploy_swarm_router
 from .api_teardown_swarm import router as teardown_swarm_router
 from .api_get_swarm_health import router as get_swarm_health_router
 from .api_check_hosts import router as check_hosts_router
+from .api_list_deckies import router as list_deckies_router
 
 swarm_router = APIRouter(prefix="/swarm")
 
@@ -27,6 +28,7 @@ swarm_router.include_router(decommission_host_router)
 # Deployments
 swarm_router.include_router(deploy_swarm_router)
 swarm_router.include_router(teardown_swarm_router)
+swarm_router.include_router(list_deckies_router)
 
 # Health
 swarm_router.include_router(get_swarm_health_router)

decnet/web/router/swarm/api_list_deckies.py

@@ -0,0 +1,47 @@
+"""GET /swarm/deckies — list decky shards with their worker host's identity.
+
+The DeckyShard table maps decky_name → host_uuid; users want to see which
+deckies are running and *where*, so we enrich each shard with the owning
+host's name/address/status from SwarmHost rather than making callers do
+the join themselves.
+"""
+from __future__ import annotations
+
+from typing import Optional
+
+from fastapi import APIRouter, Depends
+
+from decnet.web.db.repository import BaseRepository
+from decnet.web.dependencies import get_repo
+from decnet.web.db.models import DeckyShardView
+
+router = APIRouter()
+
+
+@router.get("/deckies", response_model=list[DeckyShardView], tags=["Swarm Deckies"])
+async def api_list_deckies(
+    host_uuid: Optional[str] = None,
+    state: Optional[str] = None,
+    repo: BaseRepository = Depends(get_repo),
+) -> list[DeckyShardView]:
+    shards = await repo.list_decky_shards(host_uuid)
+    hosts = {h["uuid"]: h for h in await repo.list_swarm_hosts()}
+
+    out: list[DeckyShardView] = []
+    for s in shards:
+        if state and s.get("state") != state:
+            continue
+        host = hosts.get(s["host_uuid"], {})
+        out.append(DeckyShardView(
+            decky_name=s["decky_name"],
+            host_uuid=s["host_uuid"],
+            host_name=host.get("name") or "<unknown>",
+            host_address=host.get("address") or "",
+            host_status=host.get("status") or "unknown",
+            services=s.get("services") or [],
+            state=s.get("state") or "pending",
+            last_error=s.get("last_error"),
+            compose_hash=s.get("compose_hash"),
+            updated_at=s["updated_at"],
+        ))
+    return out