feat: add language column, AI Generated category, and mine/shared filters

- Add language column (powershell/bash/python) to script_templates model and schemas
- Seed 'AI Generated' script category via migration 063
- Add mine and shared query params to list_templates endpoint

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/alembic/versions/063_add_language_to_script_templates_and_ai_.py

@@ -0,0 +1,55 @@
+"""add_language_to_script_templates_and_ai_generated_category
+
+Revision ID: 063
+Revises: 062
+Create Date: 2026-03-21 21:13:32.239533
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = '063'
+down_revision: Union[str, None] = '062'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # Add language column to script_templates
+    op.add_column(
+        'script_templates',
+        sa.Column(
+            'language',
+            sa.String(length=30),
+            nullable=True,
+            comment='Script language: powershell, bash, python',
+        ),
+    )
+
+    # Seed "AI Generated" category
+    op.execute(
+        sa.text("""
+            INSERT INTO script_categories (id, name, slug, description, icon, sort_order, is_active, created_at, updated_at)
+            VALUES (
+                'a0000000-0000-0000-0000-000000000001'::uuid,
+                'AI Generated',
+                'ai-generated',
+                'Scripts generated by the AI Script Builder',
+                'sparkles',
+                100,
+                true,
+                NOW(),
+                NOW()
+            )
+            ON CONFLICT (slug) DO NOTHING
+        """)
+    )
+
+
+def downgrade() -> None:
+    op.execute(sa.text("DELETE FROM script_categories WHERE slug = 'ai-generated'"))
+    op.drop_column('script_templates', 'language')