Motivation

Rapira permits lastUpdated: false per page. YiiPress only offers the site-wide last_updated boolean, so individual pages cannot opt in or out.

Reference: https://rapira.rs/docs/contributing#page-frontmatter

Proposed behavior

Add a nullable entry-level override resolved against the existing site-wide setting.

Acceptance criteria

• Entries can explicitly enable or disable last-updated output.
• An omitted entry setting inherits last_updated.
• Cache signatures include the effective value and source mtime only when needed.
• Add parser/renderer/cache PHPUnit coverage and document the front-matter option.