fix: restore string[] choices, optional icons, and fix nested ChoiceGroup crash

[brillout]

Why

Dependabot bump vikejs/vike#3362 (@brillout/docpress 0.16.39 → 0.16.43) breaks vike's docs CI in two ways. Both are docpress regressions in 0.16.43. This PR fixes them; with these changes vike needs no config change.

Fix 1 — +choices API backward compatibility

The icons feature (#153) changed each choice from a plain string to { name; icon; iconStyle? } with a required icon. That is a breaking change:

• Type error — configs passing string[] (like vike's choices: ['React', 'Vue', 'Solid']) no longer satisfy Config['choices'].
• Build crash — at runtime, group resolution matches by choice.name, which is undefined for plain strings, so the build throws [Wrong Usage] Missing group name for [React,Vue,Solid].

Also, requiring an icon on every choice is impractical (e.g. vike's Other server choice has no logo).

Changes:

• Choice.choices now accepts string | { name; icon?; iconStyle? }; icon is optional and a plain string is shorthand for { name }.
• Added normalizeChoice/normalizeChoices, applied at every read site (build-time resolution + the Tabs and CustomSelect components) so the rest of the code only deals with normalized objects.
• The icon <img> is rendered only when an icon is defined.

Fix 2 — crash on nested ChoiceGroupContainer

Independently, a toggleable code block (TS/JS via remarkDetype, or an npm command via remarkPkgManager) nested inside other markup (a <Warning>, a blockquote, …) within a :::Choice is emitted as a nested ChoiceGroupContainer. The choiceGroupAll injection pass return 'skip's into containers, so the nested one renders without the attribute and choiceGroupAll.some(...) throws Cannot read properties of undefined (reading 'some') during pre-rendering (hit by vike's bodyHtmlEnd and clientOnly-helper pages).

This was previously masked by the Fix‑1 build error. The minimal, safe fix here guards the access — consistent with the already‑guarded .map two lines below; the container's choices still toggle via the shared/global selector (verified in the rendered HTML).

Note: the deeper root cause is that remarkDetype/remarkPkgManager compute the nesting level from the immediate parent, so a code block nested inside non‑choice markup is mistaken for top‑level and wrongly wrapped in its own container. A more thorough fix would resolve the level from ancestors so no phantom nested container is created. Happy to follow up with that if preferred.

Verification

Against a local build of this branch linked into vike's docs:

• docpress: build ✓, test:types ✓, test:units ✓, demo vike build ✓
• vike docs (unchanged string[] config): tsc ✓ and vike build ✓ (351 pages pre-rendered)
• Type-checked string[], object-with-optional-icon, and mixed choice formats

Follow-up for vike#3362

After release, vike's bump should target the new version (≥ next patch); no change to vike's +docpress.tsx is needed thanks to the restored string[] support.

🤖 Generated with Claude Code

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Generated by Claude Code

[brillout]

@phonzammi Because Other in https://vike.dev/server#get-started doesn't have an icon.

[phonzammi]

Thank you.