Task #3: MVP API — payment-gated jobs + demo endpoint

OpenAPI spec (lib/api-spec/openapi.yaml)
- Added POST /jobs, GET /jobs/{id}, GET /demo endpoints
- Added schemas: CreateJobRequest, CreateJobResponse, JobStatusResponse,
  InvoiceInfo, JobState, DemoResponse, ErrorResponse
- Ran codegen: generated CreateJobBody, GetJobResponse, RunDemoQueryParams etc.

Jobs router (artifacts/api-server/src/routes/jobs.ts)
- POST /jobs: validates body, creates LNbits eval invoice, inserts job +
  invoice in a DB transaction, returns { jobId, evalInvoice }
- GET /jobs/🆔 fetches job, calls advanceJob() helper, returns state-
  appropriate payload (eval/work invoice, reason, result, errorMessage)
- advanceJob() state machine:
  - awaiting_eval_payment: checks LNbits, atomically marks paid + advances
    state via optimistic WHERE state='awaiting_eval_payment'; runs
    AgentService.evaluateRequest, branches to awaiting_work_payment or rejected
  - awaiting_work_payment: same pattern for work invoice, runs
    AgentService.executeWork, advances to complete
  - Any agent/LNbits error transitions job to failed

Demo router (artifacts/api-server/src/routes/demo.ts)
- GET /demo?request=...: in-memory rate limiter (5 req/hour per IP)
- Explicit guard for missing request param (coerce.string() workaround)
- Calls AgentService.executeWork directly, returns { result }

Dev router (artifacts/api-server/src/routes/dev.ts)
- POST /dev/stub/pay/:paymentHash: marks stub invoice paid in-memory
- Only mounted when NODE_ENV !== 'production'

Route index updated to mount all three routers

replit.md: documented full curl flow with all 6 steps, demo endpoint,
and dev stub-pay trigger

End-to-end verified with curl:
- Full flow: create → eval pay → evaluating → work pay → executing → complete
- Error cases: 400 on missing body/param, 404 on unknown job

lib/api-client-react/src/generated/api.schemas.ts

@@ -8,3 +8,52 @@
 export interface HealthStatus {
   status: string;
 }
+
+export interface ErrorResponse {
+  error: string;
+}
+
+export interface InvoiceInfo {
+  paymentRequest: string;
+  amountSats: number;
+}
+
+export interface CreateJobRequest {
+  /** @minLength 1 */
+  request: string;
+}
+
+export interface CreateJobResponse {
+  jobId: string;
+  evalInvoice: InvoiceInfo;
+}
+
+export type JobState = (typeof JobState)[keyof typeof JobState];
+
+export const JobState = {
+  awaiting_eval_payment: "awaiting_eval_payment",
+  evaluating: "evaluating",
+  rejected: "rejected",
+  awaiting_work_payment: "awaiting_work_payment",
+  executing: "executing",
+  complete: "complete",
+  failed: "failed",
+} as const;
+
+export interface JobStatusResponse {
+  jobId: string;
+  state: JobState;
+  evalInvoice?: InvoiceInfo;
+  workInvoice?: InvoiceInfo;
+  reason?: string;
+  result?: string;
+  errorMessage?: string;
+}
+
+export interface DemoResponse {
+  result: string;
+}
+
+export type RunDemoParams = {
+  request: string;
+};