feat(docs): inject SEO metadata into published guide bundles

[simonkrol]

SEO / discoverability:

• Added tools/build-user-guide/inject-seo-metadata.py — patches the outer bundler-shell <head> of docs/index.html and docs/site/user-guide.html (the bytes a crawler sees before any JS runs) with a real <title>, <meta name="description">, Open Graph tags, a Twitter Card type, and a canonical link, all sourced from the page's own real content. Replaces the generic "This page requires JavaScript to display" <noscript> fallback with the real <h1> and intro paragraphs. Idempotent (marker-based) and never touches the inner __bundler/template JSON span.
• tools/build-user-guide/build-user-guide.sh: wires the injector into the build pipeline (default build mode, after check-bundle-js.py passes; and --record mode, before the manifest is pinned), so both published bundles always carry the injected metadata and the manifest hash reflects it.
• docs/index.html, docs/site/user-guide.html: regenerated through the pipeline (not hand-edited). Only the outer shell changed — the inner page content is byte-identical to main (verified via SHA-256 of the extracted __bundler/template span).
• docs/site/.user-guide.manifest: re-pinned to the new output hash so build-user-guide.sh --check / make guide-check see no drift from this change.
• Added docs/social-preview.png (1200×1200) — a static PNG render of the logo mark already used on the bundler's own loading screen (#__bundler_thumbnail's inline SVG, identical in both bundles). Used as og:image, so link unfurls (Slack, LinkedIn, Facebook, and Twitter/X via its OG fallback) show a real image instead of none.
• Added docs/robots.txt — standard allow-all robots file pointing at the sitemap.
• Added docs/sitemap.xml — lists the two genuinely distinct published URLs (https://aws-solutions.github.io/konductor/ and https://aws-solutions.github.io/konductor/site/user-guide.html). Deliberately excludes internal hash-fragment routes (e.g. #/tasks), which aren't separately crawlable.

Social card tags, specifically: twitter:card is set to summary_large_image (the layout only — it carries no image of its own). No twitter:title, twitter:description, or twitter:image are set; Twitter/X falls back to og:title/og:description/og:image when those are absent, so duplicating the same values under both prefixes would have been redundant.

Known, deliberate deviation from "single bundled page, no network calls": that requirement (in tools/build-user-guide/BUILD_USER_GUIDE_PROMPT.md) is about the guide opening via file:// with no build step and no network fetch (besides the already-accepted Google Fonts link). og:image is a web convention that only works by pointing at a separately-fetchable HTTP(S) URL — it cannot be satisfied by an embedded data URI in practice (most unfurlers, including Twitter's, expect a real URL, not a data: URI). docs/social-preview.png is therefore a second static file living alongside the bundle, not embedded in it. This does not affect the file://-offline use case — nothing in the rendered page loads this image; it's metadata read only by external link-unfurling crawlers after the page is shared, never fetched by a browser opening the HTML file itself. It does mean the guide is no longer strictly a single file. Flagging this explicitly as an intentional, scoped exception rather than an oversight.

Deliberately excluded from this PR:

• README.md — doc: README updates to include links to Workshop and User Guide #32 is already open adding the GitHub Pages link there; touching it here would conflict.

Fixes # (no linked issue)

Type of Change

Build tooling (tools/build-user-guide/) and generated GitHub Pages output (docs/).

Testing

• Ran make guide-check before and after this change. One failure persists in both cases — check [10], `config` is listed as withdrawn from the guide, but cli/README.md no longer declares it — confirmed via git stash to be identical on clean main, i.e. pre-existing and unrelated to this change. No new failures introduced.
• Verified the inner __bundler/template span of both regenerated bundles is byte-identical (SHA-256) to the same span on main — only the outer shell changed.
• Verified docs/social-preview.png is a valid PNG (1200×1200, RGBA) and is staged/committed, not left untracked, so the referenced URL will resolve once published.
• Confirmed idempotency: running inject-seo-metadata.py a second time against already-patched files produces byte-identical output.
• New or changed code files carry the required SPDX header; formats without comment syntax (e.g. JSON, PNG) are exempt.

Not applicable here: npm test (no JS/TS source changed), cd cli && make test (no cli/ Rust/Python source changed — this touches tools/build-user-guide/, a separate script, not the cli/ crate), agent/skill benchmark harness (no agent or skill behavior changed).

Checklist

• My code follows the style guidelines of this project (see AGENTS.md's Code Style & Conventions)
• I have performed a self-review of my own changes
• I have commented my code where necessary
• I have made corresponding changes to the documentation
• My changes generate no new warnings — build is clean
• I have added or updated tests that prove my change works (see Testing above for the exact commands)

Notes for Reviewers

• Known pre-existing failure, not caused by this PR: make guide-check check [10] fails on main as well as on this branch (confirmed via git stash): `config` is listed as withdrawn from the guide, but cli/README.md no longer declares it — drop it from WITHDRAWN_COMMANDS. Out of scope here; flagging so it isn't mistaken for a regression from this change.
• The injector sources all copy (title, description, OG tags, noscript fallback) from the page's own real <h1> and paragraph text — nothing is invented. social-preview.png is likewise a faithful render of an asset already present in the bundle (the loading-screen SVG), not a new design.
• See the "Known, deliberate deviation" note above re: og:image and the single-file-bundle requirement — happy to discuss if a different tradeoff is preferred (e.g. dropping the image tags entirely to stay strictly single-file).
• docs/index.html and docs/site/user-guide.html are generated artifacts; please don't review them line-by-line — review inject-seo-metadata.py and the build-user-guide.sh wiring, and treat the two HTML diffs as their output.

Example Linkedin Post:

Tested Pages build: https://simonkrol.github.io/konductor/