feat(site): add Night Walker download page

[ItsFlow]

Intent

Ship a tiny public download page for Night Walker on the existing GitHub repo https://github.com/ItsFlow/night-walker. Do not create a second GitHub repo.

One-screen marketing/download page. Captain pointed at https://lawn.video/ for simplicity, not a visual clone: huge type, almost no copy, one primary button, no feature grid, no pricing tables, no "how it works" stairs. Dry. Not cute-SaaS.

Product: Night Walker is a macOS menu-bar app that turns Accessibility Color Filters on at sunset and off at sunrise. Friends download a DMG. Ad-hoc signed (right-click → Open once). Not App Store.

Motion: after load, a massive pair of sunglasses is put onto the page (over a face, a sky, or the type). Then the world shifts into Miami Vice / GTA Vice City sunset: hot magenta, cyan, orange, chrome-ish night. Optionally a second beat where the wash goes warm red / Color Filters-on. CSS/SVG animation is enough; no heavy 3D engine, no third-party design kit.

Download: primary CTA is Download. Serve the current DMG from the site. Do not require /Users/flo/Downloads/NightWalker-1.0.0.dmg at runtime for visitors — the page links a repo-hosted NightWalker.dmg. Tiny Gatekeeper line: macOS 13+, Intel or Apple Silicon, right-click → Open the first time.

A login-item is being added on a sibling Night Walker run. Ship the page with the current DMG and a stable download URL so it can be swapped later without a redesign.

Captain supersession (2026-08-20): GitHub Pages is the wrong home. Do not enable GitHub Pages. Do not treat https://itsflow.github.io/night-walker/ as acceptance. Public hosting will be a custom domain later (likely nightwalker.app or nightwalker.io on Vercel). Keep the static site files in docs/. Do not buy a domain. Finding pages-not-live must be skipped/approved as non-blocking — not fixed by enabling Pages. Do not add a GitHub Pages deploy workflow.

Constraints: stay on branch fm/nw-site from current main. The Swift app on main may still be the older name; the page is Night Walker regardless. Do not rewrite the app in this task. No Claude — Codex pipeline only. Do not touch the captain's live Night Walker/Color Filter install. Firstmate owns merge; do not merge the PR or push to the default branch.

Acceptance: PR through no-mistakes with checks green; one-screen Night Walker page with sunglasses → Miami Vice sunset motion, working Download of the DMG, Gatekeeper one-liner present. Live github.io Pages is NOT required.

Implementation on this branch: site in docs/ (index.html + NightWalker.dmg + .nojekyll); Download href is relative NightWalker.dmg; CSS/SVG only; tests/site-contract.sh HTTP contract; .github/workflows/site.yml runs that contract only (no Pages deploy).

What Changed

• Add a one-screen Night Walker download page with animated sunglasses, a Miami Vice sunset treatment, and reduced-motion support.
• Serve the bundled macOS DMG through a stable relative download link with compatibility and Gatekeeper guidance.
• Add an HTTP site contract and CI workflow that verify the page and DMG without deploying GitHub Pages.

Risk Assessment

✅ Low: The change is well-bounded and satisfies the source-verifiable intent: a static one-screen site, CSS/SVG motion, relative repo-hosted DMG download, required Gatekeeper copy, behavioral HTTP contract, and no GitHub Pages deployment.

Testing

The focused HTTP contract passed; system WebKit rendered the completed sunglasses/sunset UI correctly on desktop and mobile, and the stable relative download returned a byte-identical valid UDIF DMG. Chrome-specific capture was unavailable because Chrome is not installed, so WebKit provided the reviewer-visible evidence instead; no broad suite, app execution, or live Color Filter changes were performed.

• Evidence: Desktop rendered final state (local file: /var/folders/16/p22jkpcn0z10z3lrwkpc4yq00000gn/T/no-mistakes-evidence/01M0FBT25CGBGDA0YN75Z3AQWD/night-walker-desktop.png)
• Evidence: Mobile rendered final state (local file: /var/folders/16/p22jkpcn0z10z3lrwkpc4yq00000gn/T/no-mistakes-evidence/01M0FBT25CGBGDA0YN75Z3AQWD/night-walker-mobile.png)

Evidence: Download integrity verification

Downloaded DMG matched the repo artifact byte-for-byte (SHA-256: 94dac8d6566c489e239f7963f38e42e93c69618b78d51916cb86812ed52a330f) and hdiutil identified it as a read-only compressed UDIF image.

Evidence: HTTP download response headers

HTTP/1.0 200 OK
Server: SimpleHTTP/0.6 Python/3.14.7
Date: Thu, 20 Aug 2026 10:37:51 GMT
Content-type: application/x-apple-diskimage
Content-Length: 856754
Last-Modified: Thu, 20 Aug 2026 10:35:00 GMT

Pipeline

Updates from git push no-mistakes

✅ **intent** - passed

✅ No issues found.

✅ **Rebase** - passed

✅ No issues found.

✅ **Review** - passed

✅ No issues found.

✅ **Test** - passed

✅ No issues found.

• ./tests/site-contract.sh
• Served docs/ with python3 -m http.server 41731 --bind 127.0.0.1 --directory docs
• Attempted chrome-devtools-axi open http://127.0.0.1:41731/ (Chrome unavailable in the environment)
• Rendered /?still=1 at 1440×900 and 390×844 using macOS WKWebView and captured PNG screenshots
• Downloaded http://127.0.0.1:41731/NightWalker.dmg with curl, compared it byte-for-byte using cmp and SHA-256, and inspected it with hdiutil imageinfo

✅ **Document** - passed

✅ No issues found.

✅ **Lint** - passed

✅ No issues found.

✅ **Push** - passed

✅ No issues found.