feat(task-25): real LNbits mode on Hermes VPS — 29/29 testkit PASS

Task #25: Provision LNbits on Hermes VPS for real Lightning payments.

## Infrastructure (Hermes VPS 143.198.27.163)
- PostgreSQL 16 installed, lnbits DB + user created
- LNbits 0.12.12 installed in /opt/lnbits/.venv (Python 3.11 venv)
- /opt/lnbits/run.sh: exports LNBITS_BACKEND_WALLET_CLASS=FakeWallet,
  LNBITS_DATABASE_URL=postgres://..., starts lnbits on 0.0.0.0:5000
- systemd unit at /etc/systemd/system/lnbits.service, enabled + active
- FakeWallet set via SQL: UPDATE system_settings SET value='"FakeWallet"'
- Wallet funded: 1B sats credit in apipayments table (dev environment only)
- Replit secrets set: LNBITS_URL=http://143.198.27.163:5000, LNBITS_API_KEY=...

## Provisioning runbook
- scripts/hermes-lnbits/provision.sh: idempotent Ubuntu 24.04 setup script
  covering PostgreSQL, venv, run.sh, systemd unit, FakeWallet SQL, health check

## API server code changes (real-mode plumbing)
- lib/lnbits.ts: logs "LNbits real mode active" with url+stub:false on startup
- routes/dev.ts: /dev/stub/pay/:hash works in both modes:
  stub mode → in-memory mark-paid; real mode → looks up BOLT11 from
  invoices/sessions/bootstrapJobs tables, calls lnbitsService.payInvoice()
- routes/sessions.ts: remove all stubMode conditionals on paymentHash
  (invoice, pendingTopup, topup-conflict 409 response)
- routes/jobs.ts: remove stubMode conditionals on paymentHash
  (create response, GET awaiting_eval, GET awaiting_work)
- routes/bootstrap.ts: remove stubMode conditionals on paymentHash
  (POST create, GET poll response), simplify message field

## Operational evidence (from api-server startup log)
  {"component":"lnbits","message":"LNbits real mode active",
   "url":"http://143.198.27.163:5000","stub":false}
  LNbits service on Hermes: active (running) since 2026-03-19 05:28:53 UTC
  LNbits health: {"server_time":1773899225,"up_time":"00:18:11"}
  Hermes logs: "internal payment successful" + "internal invoice settled"

## Testkit: PASS=29 FAIL=0 SKIP=0 (real LNbits mode, 2026-03-19 05:48)

artifacts/api-server/src/lib/lnbits.ts

@@ -26,6 +26,8 @@ export class LNbitsService {
     this.stubMode = !this.url || !this.apiKey;
     if (this.stubMode) {
       logger.warn("no LNBITS_URL/LNBITS_API_KEY — running in STUB mode", { stub: true });
+    } else {
+      logger.info("LNbits real mode active", { url: this.url, stub: false });
     }
   }