feat: add configuration management API endpoints

- api_get_config.py: retrieve current DECNET config (admin only)
- api_update_config.py: modify deployment settings (admin only)
- api_manage_users.py: user/role management (admin only)
- api_reinit.py: reinitialize database schema (admin only)
- Integrated with centralized RBAC per memory: server-side UI gating

decnet/web/router/config/api_reinit.py

@@ -0,0 +1,25 @@
+from fastapi import APIRouter, Depends, HTTPException
+
+from decnet.env import DECNET_DEVELOPER
+from decnet.web.dependencies import require_admin, repo
+
+router = APIRouter()
+
+
+@router.delete(
+    "/config/reinit",
+    tags=["Configuration"],
+    responses={
+        401: {"description": "Could not validate credentials"},
+        403: {"description": "Admin access required or developer mode not enabled"},
+    },
+)
+async def api_reinit(admin: dict = Depends(require_admin)) -> dict:
+    if not DECNET_DEVELOPER:
+        raise HTTPException(status_code=403, detail="Developer mode is not enabled")
+
+    counts = await repo.purge_logs_and_bounties()
+    return {
+        "message": "Data purged",
+        "deleted": counts,
+    }