Move the documentation to Hugo and Hextra, laid out like go-fileshare's

[tannevaled]

Brings go-widgets/docs into line with go-fileshare/docs: same stack, same layout, same workflow, same versioning, same four languages.

Stack. MkDocs and mike are replaced by Hugo 0.167.0 with the tannevaled/hextra fork (submodule, v0.16.0) and go-widgets/brand (submodule, v0.1.0, tagged for this from go-widgets/brand#2). There is a navbar with a Projects menu (go-opentype, go-macos, go-freedesktop, wasmdesk), a version selector, a theme combo, search and GitHub. The teal is used as Hextra's primary colour, and table headers are #0F766E (5.5:1 for white text; the mark's own #0D9488 is 3.7:1).

Versions. go-widgets is 19 modules with no single release, so the label is the documentation's own minor version (params.docs.version: v0.2.0 → /docs/0.2/). scripts/publish-version.sh is fileshare's. It keeps the MkDocs-built 0.1 on gh-pages untouched, rewrites versions.json in mike's format, and moves latest. /docs/latest/modules/ keeps working.

Content. Two pages become 21, in EN/FR/ES/DE:

• a first application (app-template, or a bare window)
• rendering: the painter seam, the toolkit, skins
• state: MVVM (mvvm, tkbind/tuibind, mvvmtk, undo), the data spine
• surfaces: native window (7 back-ends and how Open chooses), application and tray, browser (webcanvas, wasmbox), terminal, Android, snapshots
• CI rules: mvvmlint, bricolint
• modules, and status

Facts were checked against each module's code at its newest tag. Several READMEs are behind their code: painter still lists 5 primitives (there are 7), window calls Wayland "future", and mvvmtk says toolkit never imports mvvm (it does, and exposes Label.Text() as an Observable). The pages follow the code.

Two claims of the old home page were false and are not repeated.

• "100% statement coverage as a CI gate" for every module: mvvmtk has no coverage gate.
• "Built and tested on" six architectures for every module: 12 of 19 do. bricolint's step is named "6 arches" but builds 5 (no loong64).
  The status page lists these gaps.

Translations keep every English anchor as an explicit {#id}, so relrefs with fragments resolve in every language. Each language was checked by script against the English: anchors in order, the same relrefs and URLs, identical code blocks, the same table shapes.

Verified locally

• the production build with --panicOnWarning: EN 108, FR 104, ES 106, DE 106 pages
• lychee offline with --include-fragments over the laid-out /docs/0.2/ tree: 0 errors
• the links job's 48 external URLs: all resolve
• rendered in Chrome, light and dark

Once this deploys, go-widgets/go-widgets.github.io#11 (the landing) can merge: its docs links point here.

🤖 Generated with Claude Code