xhs-saas-console v0.5.3 (frontend path fix + httpx proxy bypass)

Fixes from PR #4 (af6f299):

• Drop redundant /api prefix in 8 frontend pages (lib/api.ts already baseURL=/api)
• Drop trailing slash in /accounts/ and /scheduler/tasks/ (was 307 redirects)
• httpx.AsyncClient(trust_env=False) in v1_gateway.py for both proxy() and health_all()
  (Windows system HTTP_PROXY was turning localhost requests into 502s)

Verified locally with 3 backends up:

• xhs-saas :8080 (FastAPI + gateway)
• pbp-api :8090 (donor-screener-pbp)
• lakehouse-api :8091 (data-lakehouse)
• vite dev :5173 (HMR console)

/api/v1/health/all -> status=ok, all three services up.