feat: attacker profiles — UUID model, API routes, list/detail frontend

Migrate Attacker model from IP-based to UUID-based primary key with
auto-migration for old schema. Add GET /attackers (paginated, search,
sort) and GET /attackers/{uuid} API routes. Rewrite Attackers.tsx as
a card grid with full threat info and create AttackerDetail.tsx as a
dedicated detail page with back navigation, stats, commands table,
and fingerprints.

decnet/web/router/attackers/api_get_attacker_detail.py

@@ -0,0 +1,26 @@
+from typing import Any
+
+from fastapi import APIRouter, Depends, HTTPException
+
+from decnet.web.dependencies import get_current_user, repo
+
+router = APIRouter()
+
+
+@router.get(
+    "/attackers/{uuid}",
+    tags=["Attacker Profiles"],
+    responses={
+        401: {"description": "Could not validate credentials"},
+        404: {"description": "Attacker not found"},
+    },
+)
+async def get_attacker_detail(
+    uuid: str,
+    current_user: str = Depends(get_current_user),
+) -> dict[str, Any]:
+    """Retrieve a single attacker profile by UUID."""
+    attacker = await repo.get_attacker_by_uuid(uuid)
+    if not attacker:
+        raise HTTPException(status_code=404, detail="Attacker not found")
+    return attacker