fix(docs): register loadingIcon cast so the Empty page prerenders (unbreak Pages deploy)

[IgorShevchik]

Problem

The Deploy to Pages workflow has failed on every run since #577 (80ab3e4a, PR #275 feat(Empty): add loading and loadingIcon props). The last green deploy was #576 (PR #274). CI aborts in the Generate Docs step:

Errors prerendering:
  ├─ /b24ui/docs/components/empty/ (20839ms)
  │ ├── [500] Server Error
[error] Exiting due to prerender errors.

/docs/components/empty/ is the only failing route — every other page prerenders fine (all the "Linked from …" lines are just pages that link to it). My recent sync PRs (#279/#280/#281) merely inherited an already-broken main; they didn't cause this.

Root cause

PR #275's ported "Loading Icon" example uses:

cast:
  loadingIcon: 'LoaderClockIcon'

but LoaderClockIcon was never added to the docs castMap (in ComponentCode.vue and server/utils/transformMDC.ts). An unregistered cast hits:

if (cast && !castMap[cast]) throw new Error(`Unknown cast: ${cast}`)

during SSR → Nitro reports [500] and exits with prerender errors.

b24ui docs deliberately expose one registered demo-icon cast — RocketIcon — and every other icon example uses it (convertIcon hardcodes it in each branch). LoaderClockIcon was an un-adapted leftover from the upstream port.

Fix

• empty.md — cast loadingIcon via the registered RocketIcon.
• ComponentCode.vue + transformMDC.ts — add loadingIcon to iconsTypeList and convertIcon, so the example's displayed code shows :loading-icon="RocketIcon", consistent with the live preview (matching the existing icon/trailing-icon/… handling).

Audited all docs content: after this change, the only icon cast referenced anywhere is RocketIcon (registered) — no other latent unregistered-cast 500s.

Verification

Local full nuxt generate docs can't complete in the sandbox (ulimit -Hn is 4096 → EMFILE in @nuxtjs/mdc), but across runs the prerender reached 774 routes with zero Unknown cast/[500] errors — the empty-page crash no longer occurs. The authoritative check is this PR's Deploy to Pages run, which has the fd headroom to complete the prerender (pre-fix it finished the full crawl and failed only on the empty-page cast).

🤖 Generated with Claude Code

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Generated by Claude Code