#82 FTX-82: GitHub Actions CI (unit+integration suite)

EARS SPEC: - When a commit is pushed to main or a pull request targets the repository, the CI system shall install pinned dependencies, provision Postgres 17 and Redis service containers, apply migretti migrations to futex_test, and run the pytest suite. - The CI system shall exclude e2e-marked tests, because they require real local auth/mail/postfix/RunFlow services absent on a GitHub runner. - The test harness shall obtain its Postgres connection parameters from environment variables (host/port/user/password/dbname), defaulting to the local unix-socket values, so the same conftest runs both locally and against a TCP Postgres service container. - While resolving the test database, the harness shall refuse to run destructive setup unless the target database name ends with '_test'. - If any non-e2e test fails, then the CI system shall fail the workflow (red check).