feat: add PostgreSQL persistence layer

- adapters: SQLAlchemy implementations for all 4 repositories (Project, AssetLibrary, Asset, IngestJob)
- models: SQLAlchemy ORM models with proper schema
- database: connection config and session management
- tests: SQLAlchemy repository integration test (in-memory SQLite)
- all 7 integration tests passing

packages/adapters/sqlalchemy_impl/models.py

@@ -0,0 +1,55 @@
+from sqlalchemy import Column, DateTime, String, Text, create_engine
+from sqlalchemy.orm import declarative_base
+from datetime import datetime, timezone
+
+Base = declarative_base()
+
+
+class ProjectModel(Base):
+    __tablename__ = "projects"
+
+    id = Column(String(32), primary_key=True)
+    workspace_id = Column(String(32), nullable=False, index=True)
+    name = Column(String(100), nullable=False)
+    description = Column(Text, nullable=False, default="")
+    created_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
+
+
+class AssetLibraryModel(Base):
+    __tablename__ = "asset_libraries"
+
+    id = Column(String(32), primary_key=True)
+    workspace_id = Column(String(32), nullable=False, index=True)
+    project_id = Column(String(32), nullable=False, index=True)
+    name = Column(String(100), nullable=False)
+    kind = Column(String(20), nullable=False)
+    created_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
+
+
+class AssetModel(Base):
+    __tablename__ = "assets"
+
+    id = Column(String(32), primary_key=True)
+    workspace_id = Column(String(32), nullable=False, index=True)
+    project_id = Column(String(32), nullable=False, index=True)
+    library_id = Column(String(32), nullable=False, index=True)
+    name = Column(String(100), nullable=False)
+    storage_key = Column(String(255), nullable=False)
+    mime_type = Column(String(100), nullable=False)
+    metadata_json = Column(Text, nullable=False, default="{}")
+    created_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
+
+
+class IngestJobModel(Base):
+    __tablename__ = "ingest_jobs"
+
+    id = Column(String(32), primary_key=True)
+    workspace_id = Column(String(32), nullable=False, index=True)
+    project_id = Column(String(32), nullable=False, index=True)
+    library_id = Column(String(32), nullable=False, index=True)
+    storage_key = Column(String(255), nullable=False)
+    status = Column(String(20), nullable=False, default="pending")
+    error_message = Column(Text, nullable=False, default="")
+    result_asset_id = Column(String(32), nullable=False, default="")
+    created_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))
+    updated_at = Column(DateTime, nullable=False, default=lambda: datetime.now(timezone.utc))