Add chat_comment_mentions table migration

surfsense_backend/alembic/versions/67_add_chat_comment_mentions_table.py

@@ -0,0 +1,45 @@
+"""Add chat_comment_mentions table for @mentions in comments
+
+Revision ID: 67
+Revises: 66
+"""
+
+from collections.abc import Sequence
+
+from alembic import op
+
+revision: str = "67"
+down_revision: str | None = "66"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    """Create chat_comment_mentions table."""
+    op.execute(
+        """
+        CREATE TABLE IF NOT EXISTS chat_comment_mentions (
+            id SERIAL PRIMARY KEY,
+            comment_id INTEGER NOT NULL REFERENCES chat_comments(id) ON DELETE CASCADE,
+            mentioned_user_id UUID NOT NULL REFERENCES "user"(id) ON DELETE CASCADE,
+            read BOOLEAN NOT NULL DEFAULT FALSE,
+            created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+            UNIQUE (comment_id, mentioned_user_id)
+        );
+
+        -- Create indexes
+        CREATE INDEX IF NOT EXISTS idx_chat_comment_mentions_comment_id 
+            ON chat_comment_mentions(comment_id);
+        CREATE INDEX IF NOT EXISTS idx_chat_comment_mentions_user_unread 
+            ON chat_comment_mentions(mentioned_user_id) WHERE read = FALSE;
+        """
+    )
+
+
+def downgrade() -> None:
+    """Drop chat_comment_mentions table."""
+    op.execute(
+        """
+        DROP TABLE IF EXISTS chat_comment_mentions;
+        """
+    )