Fix SQLite locking issue in execute_write_script

The execute_write_script() method was causing SQLite database locking
errors when multiple executescript() calls ran in quick succession.

Root cause: SQLite's executescript() method has special behavior - it
implicitly commits any pending transaction and operates in autocommit
mode. However, execute_write_script() was passing these calls through
execute_write_fn() with the default transaction=True, which wrapped
the executescript() call in a transaction context (with conn:).

This created a conflict where sequential executescript() calls would
cause the second call to fail with "OperationalError: database table
is locked: sqlite_master" because the sqlite_master table was still
locked from the first operation's implicit commit.

Fix: Pass transaction=False to execute_write_fn() since executescript()
manages its own transactions and should not be wrapped in an additional
transaction context.

This was causing test_hook_extra_body_script to fail because the
internal database initialization (which calls executescript twice in
succession) would fail, preventing the application from rendering
pages correctly.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: simonw

datasette/database.py

@@ -143,7 +143,9 @@ def _inner(conn):
             return conn.executescript(sql)
 
         with trace("sql", database=self.name, sql=sql.strip(), executescript=True):
-            results = await self.execute_write_fn(_inner, block=block)
+            results = await self.execute_write_fn(
+                _inner, block=block, transaction=False
+            )
         return results
 
     async def execute_write_many(self, sql, params_seq, block=True):