docs(pages): dark theme (midnight) + drop the "Home" landing title

[rmednitzer]

Two requested tweaks to the GitHub Pages docs site (https://rmednitzer.github.io/relay-shell/).

1. Dark mode

Switches the Jekyll theme from jekyll-theme-cayman (light) to jekyll-theme-midnight — a dark theme that is part of the GitHub-Pages-supported set, so it keeps working with the legacy /docs-branch build (no remote_theme plumbing). Page content is unchanged; only the theme colors/layout differ.

The other supported dark option is jekyll-theme-hacker (black + green monospace, terminal aesthetic — arguably fitting for a shell tool). Say the word and I'll switch to that instead, or override Cayman's CSS to keep its exact layout but dark.

2. Landing tab no longer says "Home"

The browser tab read Home | relay-shell because docs/index.md front matter set title: Home. Changed it to title: Documentation, so jekyll-seo-tag renders Documentation | relay-shell.

(Setting it to relay-shell would equal the site title, which makes seo-tag fall through and append the entire site description to the tab — hence a distinct, short label.)

Notes

• Docs-only — no Python touched (ruff/mypy/pytest gate N/A); no Liquid changes (the runbook {% raw %} guard from fix(pages): guard runbook Liquid tokens so the Jekyll build succeeds #118 is untouched, and re-scanning docs/ finds no unguarded {{/{%).
• The theme is a one-line, supported-theme swap, so the Pages build stays green; the dark rendering + new tab title verify on the live site once this merges and the build redeploys.

🤖 Generated with Claude Code

---

Generated by Claude Code