Quick-setup helpers and env validation #70

Depends on: Issue #69 (optional)

Summary

Give new users a one-call setup for JWT, API key and OAuth, and a check that lists every missing environment variable.

Reference

• ts:auth/quick-setup.ts: setupJWTAuth,
• setupAPIKeyAuth,
• setupOAuthAuth,
• generateTestCredentials,
• printAuthSetupInstructions,
• validateAuthEnv.

Prior work

Closed PR #4 has nitrostack/auth/setup.py (54 lines). It imports nitrostack/auth/middleware.py from the same branch, so bring that file across or rewrite the import against current modules.

Scope

• setup_jwt_auth, setup_api_key_auth and setup_oauth_auth, each returning a configuration that the matching module accepts.
• generate_test_credentials(), documented as test-only.
• validate_auth_env(kind) -> (valid, missing) and print_auth_setup_instructions(kind).

Acceptance criteria

• Each helper's output configures its module, covered by a test.
• validate_auth_env lists every missing variable, not just the first.
• Test credentials are random on every call and are never printed by default.