chore: commit pending phase-3 work and add TEST_ACCOUNTS.md

Includes planning artifacts (03-CONTEXT, 03-DISCUSSION-LOG, 03-02-SUMMARY),
integration test script, MinIO/auth/docker fixes, and local dev account reference.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/requirements.txt

@@ -2,6 +2,7 @@ fastapi>=0.111
 uvicorn[standard]>=0.29
 python-multipart
 pydantic-settings>=2.2
+pydantic[email]>=2.0
 anthropic>=0.26
 openai>=1.30
 PyMuPDF>=1.24
@@ -16,11 +17,10 @@ sqlalchemy[asyncio]>=2.0.49
 psycopg[binary]>=3.3.4
 alembic>=1.18.4
 minio>=7.2.20
-celery[redis]>=5.6.3
-redis>=7.4.0
+celery[redis]>=5.5.0
+redis>=4.6.0
 aiosqlite>=0.20.0
 PyJWT>=2.8.0
 pwdlib[argon2]>=0.2.1
 pyotp>=2.9.0
-aioredis>=2.0.0
 slowapi>=0.1.9