chore: track alembic migrations in git

Le migrations Alembic sono essenziali per il deploy riproducibile:
rimuove la regola in .gitignore che le escludeva e aggiunge al
tracking la migration 001 (image_path) gia esistente ma mai committata.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/migrations/versions/001_add_image_path_to_recipe_and_subtask.py

@@ -0,0 +1,27 @@
+"""add image_path to recipe and subtask
+
+Revision ID: 001_image_path
+Revises:
+Create Date: 2026-02-20
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision: str = '001_image_path'
+down_revision: Union[str, None] = None
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column('recipes', sa.Column('image_path', sa.String(500), nullable=True))
+    op.add_column('recipe_subtasks', sa.Column('image_path', sa.String(500), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column('recipe_subtasks', 'image_path')
+    op.drop_column('recipes', 'image_path')