Add Docker, migrations, and initial database setup

Added Dockerfile and docker-compose.yaml for containerization. Introduced Alembic migrations with initial schema and a migration to alter column types. Added requirements.txt for dependencies and removed temp.py cleanup script. Updated .gitignore to allow tracking of migration files.

migrations/versions/bb1d9bebf8f6_.py

@@ -0,0 +1,50 @@
+"""empty message
+
+Revision ID: bb1d9bebf8f6
+Revises: 46cd3e1a3b67
+Create Date: 2025-08-07 16:49:19.511091
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'bb1d9bebf8f6'
+down_revision = '46cd3e1a3b67'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table('food_item', schema=None) as batch_op:
+        batch_op.alter_column('barcode',
+               existing_type=sa.INTEGER(),
+               type_=sa.String(),
+               existing_nullable=True)
+
+    with op.batch_alter_table('food_log', schema=None) as batch_op:
+        batch_op.alter_column('amount',
+               existing_type=sa.INTEGER(),
+               type_=sa.Float(),
+               existing_nullable=False)
+
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table('food_log', schema=None) as batch_op:
+        batch_op.alter_column('amount',
+               existing_type=sa.Float(),
+               type_=sa.INTEGER(),
+               existing_nullable=False)
+
+    with op.batch_alter_table('food_item', schema=None) as batch_op:
+        batch_op.alter_column('barcode',
+               existing_type=sa.String(),
+               type_=sa.INTEGER(),
+               existing_nullable=True)
+
+    # ### end Alembic commands ###