Fix missing view_count column migration on startup

create_all doesn't add columns to existing tables. Add _add_column_if_missing
helper that checks PRAGMA table_info and runs ALTER TABLE if needed, called
on every startup before FTS setup.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/database.py

@@ -70,13 +70,22 @@ END;
 """
 
 
+def _add_column_if_missing(raw_conn, table: str, column: str, definition: str):
+    existing = {row[1] for row in raw_conn.execute(f"PRAGMA table_info({table})")}
+    if column not in existing:
+        raw_conn.execute(f"ALTER TABLE {table} ADD COLUMN {column} {definition}")
+
+
 def init_db():
     from . import models  # noqa: F401
 
     Base.metadata.create_all(bind=engine)
-    # executescript handles multi-statement SQL including trigger BEGIN...END blocks
     raw_conn = engine.raw_connection()
     try:
+        # Column migrations — safe to run on every startup
+        _add_column_if_missing(raw_conn, "videos", "view_count", "INTEGER")
+        raw_conn.commit()
+        # executescript handles multi-statement SQL including trigger BEGIN...END blocks
         raw_conn.executescript(FTS_SETUP_SQL)
     finally:
         raw_conn.close()