Fix manifest schema build with updated Amp models

[abarmat]

Updates the Python client to use the latest Amp admin API spec, fixing the schema endpoint interface and regenerating models from the current server specification.

Key changes:

• Refresh admin.spec.json from latest Amp server and regenerate Pydantic models
• Update SchemaClient.get_output_schema() to accept tables, dependencies, and functions parameters instead of single SQL query
• Fix QueryBuilder.to_manifest() to properly pass table name and dependencies to the new schema API
• Update tests and documentation to reflect the new schema request/response structure

Resolves #27