Based on mihomo-configurator, reworked for fleet operation:

- Node registry in SQLite (better-sqlite3): URL + secret per node,
  live status probes, audit log
- Per-node REST proxy + SSE bridge (secrets stay server-side)
- Config management: validate → PUT /configs/file (patched mihomo fork)
  → persist on node → apply → version recorded in DB; rollback support
- Fleet dashboard with add-node dialog and node switcher sidebar
- All monitoring/config pages moved under /nodes/[id]/...
- Stateless password auth (unchanged from configurator)

E2E verified against a live patched mihomo node: add node + baseline
import, config push (file persisted on node, port switch with force),
version history, rollback, invalid YAML 422, SSE traffic stream.