feat(01-01): add Pydantic Settings class to config.py and update requirements.txt

- Add Settings(BaseSettings) class reading DATABASE_URL, DATABASE_MIGRATE_URL,
  MINIO_ENDPOINT, MINIO_ACCESS_KEY, MINIO_SECRET_KEY, MINIO_BUCKET, REDIS_URL,
  SECRET_KEY from environment via SettingsConfigDict (pydantic-settings v2 API)
- Instantiate settings = Settings() at module level for all callers
- Preserve legacy DATA_DIR, UPLOADS_DIR, METADATA_DIR, TOPICS_FILE, SETTINGS_FILE,
  DEFAULT_SYSTEM_PROMPT, DEFAULT_SETTINGS, ensure_data_dirs() for Wave 4 compat
- Remove filelock>=3.14 (replaced by PostgreSQL transactions per STORE-07)
- Add 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, aiosqlite>=0.20.0
- Bump pytest-asyncio to >=1.3.0 for asyncio_mode auto support

backend/config.py

@@ -2,6 +2,47 @@ import json
 import os
 from pathlib import Path
 
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    """Phase 1 Pydantic Settings — reads all Phase 1 env vars from environment or .env file."""
+
+    model_config = SettingsConfigDict(
+        env_file=".env",
+        env_file_encoding="utf-8",
+        extra="ignore",
+    )
+
+    # Data directory (legacy flat-file path — kept until Plan 05 removes it)
+    data_dir: str = "/app/data"
+
+    # PostgreSQL
+    database_url: str = "postgresql+psycopg://docuvault_app:changeme_app@postgres:5432/docuvault"
+    database_migrate_url: str = "postgresql+psycopg://docuvault_migrate:changeme_migrate@postgres:5432/docuvault"
+
+    # MinIO
+    minio_endpoint: str = "minio:9000"
+    minio_access_key: str = "docuvault_app"
+    minio_secret_key: str = "changeme_minio_app"
+    minio_bucket: str = "docuvault"
+
+    # Redis / Celery
+    redis_url: str = "redis://:changeme_redis@redis:6379/0"
+
+    # Security (Phase 2 — documented now, not read by Phase 1 code paths)
+    secret_key: str = "CHANGEME"
+
+
+settings = Settings()
+
+# ──────────────────────────────────────────────────────────────────────────────
+# Legacy flat-file constants — kept for backward compatibility through Wave 4.
+# These are consumed by services/storage.py, services/classifier.py, and
+# api/settings.py until Plan 05 rewrites those modules.
+# DO NOT DELETE until Plan 05 completes the storage service cutover.
+# ──────────────────────────────────────────────────────────────────────────────
+
 DATA_DIR = Path(os.environ.get("DATA_DIR", "/app/data"))
 UPLOADS_DIR = DATA_DIR / "uploads"
 METADATA_DIR = DATA_DIR / "metadata"

backend/requirements.txt

@@ -8,8 +8,14 @@ PyMuPDF>=1.24
 python-docx>=1.1
 pytesseract>=0.3
 Pillow>=10.3
-filelock>=3.14
 aiofiles>=23.2
 httpx>=0.27
 pytest>=8.2
-pytest-asyncio>=0.23
+pytest-asyncio>=1.3.0
+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
+aiosqlite>=0.20.0