feat: add stripe-sigma connector

[andrei-hasna]

Summary

• Add @hasna/connect-stripe-sigma package under connectors/stripe-sigma/ with real Stripe Sigma Query Runs API client (POST/GET /v1/sigma/query_runs on api.stripe.com)
• CLI: query-runs create/get, profile/config management, Bearer + Stripe-Version preview header
• Registry entry in Commerce & Finance; test-endpoints health check via balance endpoint

Test plan

• cd connectors/stripe-sigma && bun run typecheck
• bun test connectors/stripe-sigma/src/api (6 tests, mocked fetch)
• bun run typecheck (monorepo root)
• bun run build
• stripe-sigma --help smoke test
• rg scan clean (no secrets, internal refs, fake api.stripesigma.com)

[andrei-hasna]

Worker review for task 7e7abeae-b0e6-42ed-abb8-0bef90c68429.

Not merged. Current blockers:

• GitHub reports mergeable=CONFLICTING, mergeStateStatus=DIRTY, no status checks, no review decision. Local git merge --no-commit --no-ff origin/main also conflicts in src/lib/connectors/commerce-finance.ts and src/lib/test-endpoints.ts.
• API contract needs rework/confirmation: the connector calls /v1/sigma/query_runs and docs links such as https://docs.stripe.com/api/sigma/query_runs return 404. Current official Stripe OpenAPI spec only lists /v1/sigma/saved_queries/{id}, /v1/sigma/scheduled_query_runs, and /v1/sigma/scheduled_query_runs/{scheduled_query_run} under /v1/sigma.

Validation performed on PR head after installing deps with BUN_INSTALL=/tmp/bunhome due sandbox tempdir limits:

• bun run typecheck passed.
• bun test src/api passed: 6 pass, 0 fail.
• bun run build passed.

Adversarial self-review: passing local tests do not prove the connector is mergeable because they mock the unverified /sigma/query_runs path; merge is blocked until conflicts are resolved and the Stripe API surface is backed by current official docs/spec or changed to supported endpoints.