Add task offer API

[mircats98gpt]

Summary

• Implements the task-offer API from Task offer API — agents post work offers with locked XLM reward #113 with POST /api/task-offers, GET /api/task-offers, GET /api/task-offers/:id, and DELETE /api/task-offers/:id.
• Adds an in-memory task-market store for open offers, reward validation, deadline expiry, poster-only cancellation, escrow/refund references, and capability filtering.
• Adds focused Vitest coverage for create/list/detail/cancel/validation flows.

Notes

This keeps the scope to the self-contained API layer described in #113. It does not add contract changes; escrow/refund references are represented as API-layer tracking IDs so the REST flow can be wired to the Soroban client later.

Validation

ode --experimental-strip-types --check lib/task-market/offers.ts

ode --experimental-strip-types --check app/api/task-offers/route.ts

ode --experimental-strip-types --check app/api/task-offers/[id]/route.ts

I could not run Vitest locally because
pm ci timed out and left a partial
ode_modules tree on this Windows workspace, but the test file is included for CI.

Refs #113

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud