feat: kit-connect + syno-balance SPK builds, busfleet hub registration endpoint

- kit-connect SPK (ipq806x): postinst with hub registration, start-stop-status,
  connect-daemon management, Tailscale + reverse SSH tunnel integration
- syno-balance SPK (noarch, test build): SmartWAN-aware dual-WAN load
  balancer with 6-factor scoring engine, syno-daemon lifecycle
- Busfleet hub: register.sh (port pool 2230-2299), Python HTTP server,
  systemd service, port-registry.json with x4078/x5925 assignments
- .gitignore: exclude SSH keys (*_id_ed25519), SPK artifacts (*.spk)

Gitea releases:
- kit-connect v0.1-0001 → x5925-kit-connect-v1 (production)
- syno-balance v0.1-0001 → syno-balance-test-v1 (prerelease)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

hub/README.md

@@ -0,0 +1,38 @@
+# Busfleet Hub
+
+Registration endpoint for kit-connect devices. Runs on the VPS at `162.243.83.36:8080`.
+
+## Files
+
+- **register.sh** — Called per-device. Assigns a tunnel port from pool 2230-2299, records it in `port-registry.json`, returns JSON.
+- **server.py** — Minimal Python HTTP server. Routes `GET /api/register/<DEVICE_ID>` → `register.sh`.
+- **port-registry.json** — Persistent device→port mapping.
+
+## Deploy
+
+```bash
+scp hub/register.sh hub/server.py root@162.243.83.36:/opt/busfleet-hub/
+ssh root@162.243.83.36 systemctl restart busfleet-hub
+```
+
+## API
+
+```
+GET /api/register/<DEVICE_ID>
+```
+
+Response (existing device):
+```json
+{"device_id": "x5925", "tunnel_port": 2230, "tailscale_auth_key": "tskey-auth-...", "status": "existing"}
+```
+
+Response (new device):
+```json
+{"device_id": "x9999", "tunnel_port": 2231, "tailscale_auth_key": "tskey-auth-...", "status": "new"}
+```
+
+## Port Pool
+
+2230–2299. Already assigned:
+- x4078: 2226 (grandfathered)
+- x5925: 2230