fix: move build info footer

[tylerdave]

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[github-actions]

Docs Site preview: https://b496f40e.rockgarden.pages.dev

[claude]

Previously flagged footer placement bug is now fixed. Moving {% block footer %} inside the max-w-4xl mx-auto div correctly constrains the footer and its border-t separator to the content width. Good call.

One concern with the strip_content_title change in builder.py — see inline comment.

[claude]

Bug: strip_content_title is now called unconditionally for all pages, including those with no frontmatter title. For a page like analysis.md starting with # Introduction (a section heading, not the document title), that heading will be silently stripped while the template's {% block heading %} separately renders <h1>analysis</h1> from the filename. The existing tests only cover the case where the leading H1 matches the derived title (my-page.md + # My Page). Previously the guard if page.frontmatter.get("title") ensured stripping only happened when the template title and content H1 were guaranteed to be the same heading.