Make --dbname and --dbuser optional when SQLite integration is active

[Copilot]

wp config create unconditionally requires --dbname and --dbuser, making it impossible to create a config for a SQLite-backed WordPress install without supplying MySQL credentials that will never be used.

Changes

• Optional synopsis params: --dbname and --dbuser are now [--dbname] / [--dbuser] in the docblock synopsis.
• SQLite detection: New is_sqlite_integration_active() checks for SQLITE_DB_DROPIN_VERSION in wp-content/db.php (reads first 8 KB only).
• Conditional validation: When SQLite is not detected, missing --dbname or --dbuser still produces an explicit error — existing MySQL/MariaDB behaviour is unchanged.
• Skip MySQL check for SQLite: The mysqli connection check is bypassed entirely when SQLite is detected, so --skip-check is not required.
• New @require-sqlite Behat scenario: Verifies wp config create succeeds without --dbname/--dbuser when the SQLite drop-in is present.

# SQLite install — now works without MySQL credentials
$ wp config create --skip-salts --skip-check
Success: Generated 'wp-config.php' file.

# MySQL install — still errors clearly if params are omitted
$ wp config create --skip-check
Error: Parameter errors:
missing --dbname parameter (Set the database name.)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!