Initial commit: Pixel AI comic/video creation platform

- FastAPI backend with SQLModel, Alembic migrations, AgentScope agents
- Next.js 15 frontend with React 19, Tailwind, Zustand, React Flow
- Multi-provider AI system (DashScope, Kling, MiniMax, Volcengine, OpenAI, etc.)
- All HTTP clients migrated from sync requests to async httpx
- Admin-managed API keys via environment variables
- SSRF vulnerability fixed in ensure_url()

backend/alembic/versions/add_provider_to_tasks.py

@@ -0,0 +1,42 @@
+"""add provider to tasks
+
+Revision ID: add_provider_to_tasks
+Revises: bfac9b8e32f5
+Create Date: 2024-02-11
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'add_provider_to_tasks'
+down_revision = 'bfac9b8e32f5'
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    """Add provider column to tasks table"""
+    # Add provider column (nullable, indexed)
+    op.add_column('tasks', sa.Column('provider', sa.String(), nullable=True))
+    
+    # Create index on provider column for faster queries
+    op.create_index(op.f('ix_tasks_provider'), 'tasks', ['provider'], unique=False)
+    
+    # Optional: Migrate existing data by extracting provider from params
+    # This is a data migration that can be run separately if needed
+    op.execute("""
+        UPDATE tasks 
+        SET provider = params->>'provider'
+        WHERE params->>'provider' IS NOT NULL
+    """)
+
+
+def downgrade() -> None:
+    """Remove provider column from tasks table"""
+    # Drop index first
+    op.drop_index(op.f('ix_tasks_provider'), table_name='tasks')
+    
+    # Drop column
+    op.drop_column('tasks', 'provider')