docs: add llms.txt for LLM agents and web crawlers (#576)

[grzanka]

Closes #576.

What

Adds an llms.txt at the repository root following the llmstxt.org specification, and wires it into the GitHub Pages deployment so it is also served at the live root URL.

Why

AI coding assistants and web-crawling LLMs benefit from a concise, standardized entry point into the project rather than ingesting the entire docs/ tree. llms.txt acts as an intelligent table of contents — it surfaces the high-level architecture and constraints inline, and links out to deep-dive markdown files that an agent can fetch only when needed.

Changes

• llms.txt (new, repo root):
  • Project summary (Svelte 5, JSROOT, Emscripten WASM, client-side).
  • Core technical constraints — Svelte 5 runes only (no legacy export let/stores/onMount), TS strict, Tailwind v4, shadcn-svelte + Bits UI, WASM only via the TS wrapper, Prettier/Conventional Commits.
  • Agent operational instructions — direct links to CLAUDE.md, AGENTS.md, CHANGELOG-AI.md.
  • High-level documentation — docs/03-architecture.md, docs/06-wasm-api-contract.md, docs/07-testing-strategy.md, and more, each with a one-line description.
  • Architecture decisions — direct links to all 13 ADRs in docs/decisions/.
  • Feature specifications and an Optional section for roadmap/wireframes.
• .github/workflows/deploy.yml: the Build SvelteKit app step now runs cp llms.txt build/llms.txt after pnpm build, so the file is served at https://aptg.github.io/web_dev/llms.txt. This copy-on-deploy approach avoids cross-platform symlink issues.
• CHANGELOG-AI.md: session entry.

Acceptance criteria

• llms.txt exists at the repository root and follows the markdown formatting spec.
• Links to critical architectural files, ADRs, and outlines core technical constraints.
• deploy.yml updated to copy llms.txt to the build output.
• Live GitHub Pages URL serves the file — verifiable after this merges and the deploy workflow runs.

pnpm format:check passes.

https://claude.ai/code/session_01GchD3PQ3zcQXV6MYvctCgj

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[Copilot]

Pull request overview

Adds an llms.txt entrypoint for LLM agents/web crawlers and ensures it’s included in the GitHub Pages artifact so it can be fetched from the deployed site, with an accompanying AI changelog entry.

Changes:

• Add root-level llms.txt following llmstxt.org conventions, linking to key project docs/ADRs/specs and stating non-negotiable stack constraints.
• Update GitHub Pages deploy workflow to copy llms.txt into the static build output (build/llms.txt).
• Append an AI session entry to CHANGELOG-AI.md.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
llms.txt	Introduces an LLM-oriented table of contents for architecture/constraints and curated doc links.
.github/workflows/deploy.yml	Copies llms.txt into build/ so it’s published by the Pages deploy.
CHANGELOG-AI.md	Records the session and the documentation/deploy wiring change.

[grzanka]

Good catch. Addressed in 9efca16 — added a note near the top of llms.txt stating that the links are relative to the repository root and, when the file is read from the deployed Pages site, must be resolved against the canonical repo (https://github.com/APTG/dedx_web, e.g. docs/03-architecture.md → .../blob/master/docs/03-architecture.md). Kept the links relative so IDE plugins scanning a checkout — the primary audience — can open the local files directly.

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Generated by Claude Code

[grzanka]

Addressed in 9efca16 — added the session log at docs/ai-logs/2026-06-05-issue-576-llms-txt.md, linked it from the changelog entry via the required **Log:** line, and indexed it in docs/ai-logs/README.md.

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