Make README a quick start and split detailed documentation

[bcomnes]

Summary

Closes #299.
This documentation change is independent of the watch stack and based on master.

• Replace the 3,000-line README with an introduction, minimal successful build, core source-to-output model, and documentation links.
• Move detailed reference material into twelve topic pages plus a documentation index under docs/.
• Add a shared docs layout with path-based breadcrumbs above and below documentation pages, following the breadcrum.net convention.
• Preserve moved README bookmarks with a collapsed compatibility index, documentation-site redirects, and anchors usable by both GitHub and the generated site.
• Update migration/reference links, point excluded example/source links to GitHub, and fix introductory/editorial wording.
• Use one sentence per line for moved prose.

Validation

• Full npm test passed outside the restricted runner.
• Five breadcrumb unit tests cover the docs index, topic pages, loose migration pages, nested paths, relative links under a deployment prefix, and HTML escaping.
• npm run build:domstack passed with all new documentation pages included.
• An ad hoc generated-site check passed all 414 local links/anchors across 23 pages and verified paired breadcrumbs on all 15 documentation pages.
• Chromium checks passed for legacy README bookmarks and hash-change navigation, breadcrumb navigation, and mobile/desktop table-of-contents transitions.
• The README's minimal source fixture builds successfully to public/index.html with the documented content and default layout.

Notes

The example reference uses docs/example-projects/ because the documentation build intentionally excludes directories named examples.
The existing migration guides remain separate documents with updated moved-reference links and the shared breadcrumb layout.

[coveralls]

Coverage Report for CI Build 34013083643

Coverage increased (+0.5%) to 94.694%

Details

• Coverage increased (+0.5%) from the base build.
• Patch coverage: 11 uncovered changes across 1 file (33 of 44 lines covered, 75.0%).
• No coverage regressions found.

Uncovered Changes

File	Changed	Covered	%
layouts/docs/docs.layout.js	44	33	75.0%

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	7350
Covered Lines:	7113
Line Coverage:	96.78%
Relevant Branches:	1414
Covered Branches:	1186
Branch Coverage:	83.88%
Branches in Coverage %:	Yes
Coverage Strength:	174.6 hits per line

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💛 - Coveralls

[bcomnes]

For the sub-pages, can you adopt a docs breadcrumb convention similar to the docs in https://github.com/hifiwi-fi/breadcrum.net/tree/master/packages/web/client/layouts/docs

[bcomnes]

Implemented in 04ddfa0, following the shared-layout convention from breadcrum.net.

All topic pages, the docs index, and both migration guides now select layout: docs and receive path-derived breadcrumbs above and below their content.
The breadcrumbs use slash separators, retain a Home link, and mark the current page with aria-current="page".
Relative parent links work for both directory pages and standalone migration guides, including deployments under a URL prefix.
The existing responsive table of contents is preserved, with no new dependencies.

Validation passed: full npm test, five breadcrumb unit tests, the documentation build, all 414 local links/anchors across 23 generated pages, and Chromium checks for breadcrumb navigation, mobile/desktop layout transitions, and legacy bookmarks.