- Remove dead _humanize_timestamp helper from css_template/schemas.py and
theme/schemas.py (never called; database/schemas.py has the canonical copy)
- Add uuid field to CssTemplateInfo and serialize_css_template_object
(CssTemplate inherits UUIDMixin)
- Add uuid to CSS_TEMPLATE_DEFAULT_COLUMNS alongside theme's existing uuid
- Register css_template and theme in get_schema tool so LLMs can discover
column/filter/sort metadata for both new domains
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>