fix(nav): wrap header links on narrow viewports

[TimeToBuildBob]

Why

The site header is a single nowrap flex row of six links. At a 390px viewport the document grew to ~510px (Projects ended at 436px, Wiki at 510px), so the page scrolled sideways even when the article itself fit. Reproduced while verifying the cancellation post; this is a layout bug, not a post issue.

Change

In assets/css/tailwind.css (source; styles.css is generated):

• flex-wrap so extra links drop to the next row instead of stretching the page
• whitespace-nowrap on each link so labels stay intact
• Slightly tighter row gap on small screens (gap-x-4 gap-y-2, sm:gap-6)

Verification

Playwright against the local Jekyll build (system Chrome, pages fulfilled from _site, no live deploy). Overflow = documentElement.scrollWidth - innerWidth.

Page	Viewport	Overflow	Nav	Links
/, /blog/, /about/, /projects/, /wiki/	390×844	0	wraps; Projects+Wiki on row 2	all 6 visible
same	320×568	0	wraps; Blog+Projects+Wiki on row 2	all 6 visible
same	1280×800	0	single row (64px tall)	all 6 visible

Desktop layout is unchanged: one row, same order, every link reachable.

Notes

• Does not touch the cancellation-post worktree or PR.
• Generated assets/css/styles.css is gitignored; CI rebuilds CSS on make build.

[TimeToBuildBob]

Local verification (system Chrome, _site fulfilled, no live deploy):

• 390×844: overflow 0, nav wraps, Projects + Wiki on row 2, all 6 links visible
• 320×568: overflow 0, Blog + Projects + Wiki on row 2, all 6 links visible
• 1280×800: overflow 0, single 64px row, all 6 links reachable

Will squash-merge once CI is green, then re-check the deployed header.

[TimeToBuildBob]

🤖 AI code review

Safe to merge — no P0/P1 findings

Confidence 5/5

✅ No findings. The diff looks correct to me on this pass.

_{Reviewed a2eb0c13033e · openrouter/deepseek/deepseek-v4-flash-0731 · llm (in-band) engine · 47s · about this reviewer}

_{Maintainer commands}

_{@TimeToBuildBob review (own line) — fresh review · @TimeToBuildBob fix — a worker acts on the findings. Once per comment; 👀 = received.}