shakapacker.com: add llms.txt and a real examples page with starter repos

[justin808]

Part of the docs & demos tracking issue: shakacode/reactonrails.com#140 (P0).

Problem

Verified 2026-07-02:

• shakapacker.com/llms.txt returns 404. reactonrails.com already ships a well-structured llms.txt route map; Shakapacker should match, since AI-assisted setup is a primary onboarding path for the stack.
• shakapacker.com/examples is a thin "Resources" hub (changelog, repo, migration/troubleshooting guides). There are no example apps, demos, or sample configurations anywhere on the site — while the homepage's comparison table invites evaluation against Vite Ruby, jsbundling-rails, etc.

Work

• Add llms.txt (mirror the reactonrails.com pattern: canonical entry points, task-based navigation, package pairing notes for shakapacker/shakapacker-rspack/shakapacker-webpack)
• Turn /examples into a real examples page with minimal, cloneable starter repos:
  • React + TypeScript + Rspack
  • Tailwind CSS setup
  • CSS modules
  • SSR-ready config (the shape react_on_rails consumes)
• Cross-link the stack story: Shakapacker as the bundler layer under React on Rails / React on Rails Pro, linking to reactonrails.com examples for the full-stack demos

Acceptance criteria

• llms.txt resolves and follows the reactonrails.com structure; /examples shows at least 3 runnable starter repos with source links.

🤖 Generated with Claude Code

Code pointers (post-transfer note: this repo owns the site presentation)

• This repo mirrors reactonrails.com's structure: Docusaurus site under prototypes/docusaurus/
• /examples page already exists as a site-owned page: prototypes/docusaurus/src/pages/examples.tsx — replace the thin resources hub with real example cards (live/source links, same card pattern as reactonrails.com's examples page)
• llms.txt: serve from prototypes/docusaurus/static/llms.txt — mirror however the reactonrails.com repo produces its llms.txt (check that repo's scripts/ for a generator before hand-writing)
• Canonical docs markdown stays in shakacode/shakapacker docs/; the starter example repos are new repos under the shakacode org (cross-file follow-ups there when created)