CSV import fixes

- Fix not being able to create table while importing
    * The behavior now aligns with SQLite so that if the table already
      exists, all the rows are treated as data. If the table doesn't exist,
      the first row is treated as the header from which column names for the
      new table are populated.
- Insert in batches instead of one at a time

testing/cli_tests/cli_test_cases.py

@@ -228,6 +228,30 @@ def test_import_csv_skip():
     shell.quit()
 
 
+def test_import_csv_create_table_from_header():
+    shell = TestTursoShell()
+    shell.run_test("open-memory", ".open :memory:", "")
+    # Import CSV with header - should create table automatically
+    shell.run_test(
+        "import-csv-create-table",
+        ".import --csv ./testing/test_files/test_w_header.csv auto_table",
+        "",
+    )
+    # Verify table was created with correct column names
+    shell.run_test(
+        "verify-auto-table-schema",
+        ".schema auto_table",
+        "CREATE TABLE auto_table (id, interesting_number, interesting_string);",
+    )
+    # Verify data was imported correctly (header row excluded)
+    shell.run_test(
+        "verify-auto-table-data",
+        "select * from auto_table;",
+        "1|2.0|String'1\n3|4.0|String2",
+    )
+    shell.quit()
+
+
 def test_table_patterns():
     shell = TestTursoShell()
     shell.run_test("tables-pattern", ".tables us%", "users")
@@ -304,6 +328,7 @@ def main():
     test_import_csv()
     test_import_csv_verbose()
     test_import_csv_skip()
+    test_import_csv_create_table_from_header()
     test_table_patterns()
     test_update_with_limit()
     test_update_with_limit_and_offset()