docs: Ledger Live integration, contract deploy learnings, NEXT_STEPS updates

- ADD_CHAIN138_TO_LEDGER_LIVE: Ledger form done; public code review repo bis-innovations/LedgerLive; init/push commands
- CONTRACT_DEPLOYMENT_RUNBOOK: Chain 138 gas price 1 gwei, 36-addr check, TransactionMirror workaround
- CONTRACT_*: AddressMapper, MirrorManager deployed 2026-02-12; 36-address on-chain check
- NEXT_STEPS_FOR_YOU: Ledger done; steps completable now (no LAN); run-completable-tasks-from-anywhere
- MASTER_INDEX, OPERATOR_OPTIONAL, SMART_CONTRACTS_INVENTORY_SIMPLE: updates
- LEDGER_BLOCKCHAIN_INTEGRATION_COMPLETE: bis-innovations/LedgerLive reference

Co-authored-by: Cursor <cursoragent@cursor.com>

multi-chain-execution/src/api/server.ts

@@ -0,0 +1,24 @@
+import express from 'express';
+import intentRoutes from './intent-routes.js';
+import executionRoutes from './execution-routes.js';
+import mirrorRoutes from './mirror-routes.js';
+import adminRoutes from './admin-routes.js';
+import routeRoutes from './route-routes.js';
+import { circuitBreakerMiddleware, healthRoutes } from './observability.js';
+
+const app: express.Express = express();
+app.use(express.json());
+app.use(circuitBreakerMiddleware);
+app.use(intentRoutes);
+app.use(executionRoutes);
+app.use(routeRoutes);
+app.use(mirrorRoutes);
+app.use(adminRoutes);
+app.use(healthRoutes);
+
+const port = parseInt(process.env.PORT ?? '3001', 10);
+app.listen(port, () => {
+  console.log(`Multi-chain execution API listening on port ${port}`);
+});
+
+export { app };