feat(platform-ui): add Platform UI dashboard + developer playground

[telivity-otaip]

Summary

A new React/Vite app at examples/platform-ui/ plus the read-only telemetry endpoints that back it. Two views:

• Dashboard — operational overview: total/active/stub agent counts, full agent registry with filter/sort/group-by-domain, adapter cards driven by env-var presence, health sidebar (uptime, requests, OTAIP version).
• Playground — split-panel request builder + response viewer with three modes:
  • Search: full flight-search form against the configured adapter.
  • Agent: picker over every discovered agent. Whitelisted agents (v1: 0.1 AirportCodeResolver) execute end-to-end; everything else returns a clear 501 with a "not yet wired" hint.
  • Adapter: direct search / price / isAvailable against the configured adapter.

Response viewer has Formatted / Raw / Timeline tabs and a last-10 in-memory request history with one-click replay.

Why

OTAIP currently ships an OTA reference app (examples/ota) — a booking demo. There was no UI for OTAIP itself: no view of the agent registry, no view of adapter configuration, no way to poke at agents. This PR adds that — Stripe Dashboard-style control plane for travel AI agents.

Backend changes

• @otaip/core gains src/discovery/agent-discovery.ts (moved verbatim from CLI; tweaked repoRoot() to walk up to pnpm-workspace.yaml rather than counting directories — more robust for both source and built consumers).
• @otaip/cli agent-discovery.ts shrinks to a re-export from @otaip/core; every existing import path keeps working.
• OTA Fastify server gains /api/platform/* (read-only telemetry, rate limit raised to 5 000/min so dashboard polling can't trip the global 100/min cap) and /api/playground/* (execution surface, AJV body schemas on every state-mutating route). One onRequest hook updates the dashboard's last-request timestamp.
• 12 new test cases across platform.test.ts + playground.test.ts, Fastify inject() + MockOtaAdapter mirroring the existing search.test.ts shape.

Frontend changes

examples/platform-ui/ — Vite + React 18 + TypeScript strict + Tailwind + react-router-dom. ~30 files: tooling (6), src components (8), src pages (2), src API client (2), styling/config (4). Tailwind only — no MUI/Ant per the brief's "no heavyweight component library" rule. JSON viewer is a hand-rolled <pre> + copy button (no syntax-highlighter dep).

Vite proxies /api → http://localhost:3000 in dev (override with OTA_SERVER_URL), so the browser sees same-origin and the existing CORS_ORIGIN env-var path stays untouched.

Curated agent whitelist

Generic agent execution requires PipelineOrchestrator + PipelineSession plumbing for every agent that has a Zod-typed contract. Doing that for 70+ agents would mean importing every package at boot. Instead the catalog endpoint surfaces all agents (so the picker works) but the executable_ids set starts at one — 0.1 AirportCodeResolver, the agent CLAUDE.md cites as the canonical reference pattern. Non-whitelisted IDs render a clear "not yet wired for playground execution" banner in the form area; submitting returns 501 with a pointer to the catalog. Adding more agents is a single object-literal entry in playground-service.ts.

Out of scope

• Production packaging of the Vite app (Fastify serving the built dist/). Acceptance criteria stop at pnpm dev end-to-end; deferred.
• Per-component unit tests on the React side. The brief asks for tests on the new endpoints — those land. UI is verified via tsc strict + manual checks.
• Adapter book exposed through the playground — intentionally read-only.

Test plan

• pnpm --filter @otaip/platform-ui typecheck — clean.
• pnpm --filter @otaip/ota-example typecheck — clean.
• pnpm --filter @otaip/cli typecheck — clean (uses the re-exported discoverAgents).
• pnpm exec vitest run examples/ota — 100 passed across 9 files (88 existing + 12 new).
• Manual: pnpm --filter @otaip/ota-example dev then pnpm --filter @otaip/platform-ui dev. Open http://localhost:5173:
  • Dashboard renders agent table grouped by domain; counts match pnpm cli agents.
  • Adapter cards reflect DUFFEL_API_KEY / HOTELBEDS_API_KEY env state.
  • Playground search returns offers from the mock or live adapter.
  • Playground agent → 0.1 with {"code":"JFK","code_type":"iata"} returns the resolved JFK record.
  • Playground agent → any other ID renders the "not yet wired" banner; clicking Execute returns 501 with the catalog hint.

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