Migrate 28 templates to use the new partial system

[briananders]

Summary

Builds on top of #65 (the partials foundation). Sweeps through post and top-level templates and replaces the repeated section + content-wrapper + blockquote markup with calls to the partials. Once #65 merges, this PR's diff will reduce to just the migration changes.

This is the aggressive variant — most templates that cleanly fit the partials are migrated.

Templates migrated (28)

Pattern	Templates
Section wrappers	28 templates (97+ <section> instances)
Blockquotes with cite + blockLink	6 templates: 2d-automaton, cellular-automaton, moire-patterns, moire-pattern-colors, last-fm, polyrhythm
Toast notifications	wordle-solver, wordle-solver-2
Results displays	wordle-solver (1), wordle-solver-2 (2)

Top-level: index.html.ejs (contributions section), about.ejs, drums.ejs (intro section), 404.html.ejs.

Posts: 2d-automaton, ant-life-simulator, blue-green, canvas-static, cellular-automaton, coin-flip, color-canvas, design-system, earth-rotating-sprite-animation, last-fm-scrobbles, last-fm, minesweeper, moire-pattern-colors, moire-patterns, music-news, polyrhythm, raining-light-effect, raining-paint, sound-frequency-slider, sticky-stacky, unique-stars, wordle-solver-2, wordle-solver, yahtzee.

Two partial fixes along the way

While migrating I discovered a collision: the page's front-matter title was leaking through the {...locals} spread, so calling partial('section/open', {...locals}) without an explicit title rendered a duplicate page heading inside every section.

• Rename title -> sectionTitle in section/open.ejs
• Rename title -> resultsTitle in results.ejs
• Update design-system.ejs callsites to use the new names

This is the same kind of collision that previously forced inputName / helpText in the form partials.

Templates left unmigrated (by design)

These don't fit the partials cleanly:

• Article-based "tip" posts — my-favorite-aliases, my-favorite-git-aliases, my-git-config, how-to-get-rid-of-untracked-files-from-your-git-branch, how-to-git-merge-without-being-prompted-for-a-message, how-to-match-the-height-of-sibling-elements, quality-podcasts. These use <article class="content"> as the page wrapper.
• Templates with <header> wrappers around headings — in-view-text-animation, interview-question, vertically-center-siblings, reverse-hover-state, browser-and-device-diagnostics. Migrating would lose the semantic header element.
• Custom wrappers / no section — wordscapes-solver (uses <div class="container section">), lissajous-curve, line-circle-rotator, paint, imdb-ratings (uses .movies-container), circle-multiplier, making-animations-with-squares, using-canvas-to-make-patterns-with-circles, circle-wave-illusion.

Verification

• npm test — passes (build + golden tests)
• npm run build:golden — clean, no errors
• Golden output for migrated pages was diffed against pre-migration HEAD. Differences fall into three buckets:
  • 0 lines — byte-identical: 16 templates (minesweeper, canvas-static, coin-flip, color-canvas, raining-light-effect, blue-green, sound-frequency-slider, raining-paint, ant-life-simulator, unique-stars, sticky-stacky, music-news, about, drums, index, 404)
  • Whitespace + noWidows typography fixes — 7 templates, 4-16 lines each (yahtzee, polyrhythm, last-fm, moire-patterns, moire-pattern-colors, 2d-automaton, cellular-automaton). noWidows() adds   before the last word in headings to prevent widows.
  • Accessibility + semantic improvements — 4 templates (wordle-solver, wordle-solver-2, last-fm-scrobbles, earth-rotating-sprite-animation): toast got role="status", aria-live="polite", and inner semantic spans; results count got aria-live="polite"; some code blocks have 2-space-less indentation inside <pre>.

Not in this PR

• No golden/ updates committed. Visual-diff baselines for the affected pages will need refreshing in a follow-up "new goldens" commit (matches the existing repo convention seen in commit ad48ae1).
• No SCSS or JS changes.

Test plan

• npm run build:golden succeeds.
• npm test passes.
• Migrated pages diff to semantically equivalent HTML (see breakdown above).
• (Reviewer) npm start and spot-check a handful of migrated pages in the browser — especially polyrhythm, wordle-solver, last-fm, drums, and the homepage.
• (Reviewer) Optional: regenerate golden/ and commit as a follow-up.

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