[Albertito-AI]

The contributor guide omits the configuration argument required by tests/fixtures.py. The metadata example therefore writes configuration into fixtures-metadata.json, while the plugin example fails with Error: Metadata should end with .json.

This updates both examples to supply separate configuration and metadata filenames, includes --recreate so they work after the preceding database-generation step, and loads the generated configuration with -c when starting Datasette.

Verification:

• Reproduced both original outcomes against main.
• Ran the corrected fixture commands sequentially in a temporary directory.
• Verified the generated JSON and all six copied plugin files.
• Used the documented server arguments to check the homepage metadata, loaded plugins and the stored neighborhood_search query.
• Documentation tests: 13 passed, 143 subtests passed.
• Sphinx HTML build with warnings treated as errors, blacken-docs, Cog and git diff --check all passed.

AI assistance: this patch and its validation were prepared with ChatGPT. The checks listed above were executed locally; a separate AI review also reran the fixture and server-example checks.