chore(examples): refresh complete integration example

[Jayking40]

chore(examples): refresh complete-integration example

Summary

Rewrites examples/complete-integration.ts to reflect the billing, vault, and gateway subsystems currently supported by the backend. The previous example only demonstrated health checks and PostgreSQL-backed billing idempotency. The refreshed version exercises every in-memory service end-to-end — vault creation, funding, API gateway proxy with rate limiting and billing, usage event recording, and revenue settlement — all without requiring a database or Stellar node.

Changes

• Rewrote the complete integration example to demonstrate a linear, 7-step walkthrough:
  1. Health check
  2. Vault creation (one per user per network)
  3. Vault funding (simulated on-chain deposit via balance snapshot update)
  4. API gateway proxy (API-key validation → rate-limit check → billing deduction → upstream forward → usage recording)
  5. Usage event inspection
  6. Revenue settlement batch (pays developers from accumulated usage fees)
  7. Final balance review
• Removed PostgreSQL dependency from the example — all state is now in-memory, making it truly copy-paste friendly
• Added contracts docs links in comments (https://github.com/CalloraOrg/callora-contracts)
• Added 11 integration tests covering the full vault + billing + gateway + settlement lifecycle:
  • Health check returns ok
  • Vault create, fund, and balance query
  • Duplicate vault rejection (409)
  • Vault 404 when not found
  • Gateway proxies and deducts billing credit
  • Gateway rejects missing API key (401)
  • Gateway rejects insufficient balance (402)
  • Gateway rejects rate-limited requests (429)
  • Settlement pays developer when threshold is met
  • Settlement skips when below minimum payout
  • Full end-to-end lifecycle test
• Updated examples README to document the refreshed endpoints and usage

Testing

PASS src/tests/complete-integration.test.ts Complete Integration — Vault + Billing + Gateway + Settlement ✓ health check returns ok (128 ms) ✓ creates a vault, funds it, and queries the balance (98 ms) ✓ rejects duplicate vault creation for same user and network (24 ms) ✓ returns 404 for vault balance when vault does not exist (14 ms) ✓ proxies a request through the gateway, deducts credit, and records usage (42 ms) ✓ returns 401 when API key is missing (18 ms) ✓ returns 402 when consumer has insufficient balance (16 ms) ✓ returns 429 when rate limited (10 ms) ✓ settles revenue after enough usage accumulates (106 ms) ✓ settlement skips when below minimum payout threshold (3 ms) ✓ end-to-end: vault → gateway → settlement lifecycle (99 ms)

Tests: 11 passed, 11 total

No existing tests were modified or broken. Pre-existing failures (Prisma generated client, pg-mem type mismatches, Node.js version incompatibility with ESLint 10) remain unchanged.

Security / data-integrity notes

• The example uses in-memory stores only — no sensitive data is persisted
• Input validation is applied on all endpoints (required fields, 400/404/409 responses)
• BigInt is used for vault balance snapshots to avoid floating-point precision issues

Closes #157

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[greatest0fallt1me]

resolve the conflicts

[Jayking40]

Conflict resolved