feat: add database fields for compression tracking

- Add is_compressed boolean flag to PasteEntity
- Add original_size integer field (nullable)
- Create Alembic migration for new columns
- Backward compatible: existing pastes get is_compressed=false

Author: Pdzly

backend/alembic/versions/6c5a2c764fb8_add_compression_fields.py

@@ -0,0 +1,34 @@
+"""add compression fields
+
+Revision ID: 6c5a2c764fb8
+Revises: 0ed6c1042110
+Create Date: 2025-12-25 13:23:44.911166
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = '6c5a2c764fb8'
+down_revision: Union[str, Sequence[str], None] = '0ed6c1042110'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column('pastes', sa.Column('is_compressed', sa.Boolean(), server_default='false', nullable=False))
+    op.add_column('pastes', sa.Column('original_size', sa.Integer(), nullable=True))
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column('pastes', 'original_size')
+    op.drop_column('pastes', 'is_compressed')
+    # ### end Alembic commands ###

backend/app/db/models.py

@@ -1,4 +1,4 @@
-from sqlalchemy import TIMESTAMP, UUID, Column, Integer, String, func, text
+from sqlalchemy import TIMESTAMP, UUID, Boolean, Column, Integer, String, func, text
 
 from app.db.base import Base
 
@@ -18,6 +18,8 @@ class PasteEntity(Base):
     )
 
     content_size = Column(Integer, nullable=False)
+    is_compressed = Column(Boolean, nullable=False, server_default='false')
+    original_size = Column(Integer, nullable=True)
 
     creator_ip = Column(String)
     creator_user_agent = Column(String)