feat(icons): auto-register icons used by library components

[kelsos]

Summary

Library-internal icons (e.g. lu-calendar-days in RuiDateTimePicker, lu-clock in RuiTimePicker, the dozens used by RuiCalendar, RuiCheckbox, RuiDataTable, etc.) were never registered automatically — every consumer would have to add them via the plugin's include option, or hit a runtime "Icons "..." not found" warning the first time the component rendered.

Now:

• A new scripts/scan-library-icons.ts step (run from dist-build.mjs after web-types) scans src/components/**/*.{vue,ts} (excluding specs/stories) and writes the validated icon list to dist/library-icons.json.
• ruiIconsPlugin reads dist/library-icons.json at configResolved and seeds its scanResult.icons with this baseline.
• Net effect: every consumer gets all 30 library-baseline icons for free, on top of whatever the plugin auto-detects in their own source and whatever they pass via include.

Verified the example app's plugin now logs Loaded 30 baseline icons used by library components and the detected-icon count went from 31 → 56.

Test plan

• pnpm run typecheck clean
• pnpm -w run lint clean
• pnpm --filter @rotki/ui-library run test:run (1072 pass)
• pnpm run test:e2e (280 pass)
• pnpm --filter @rotki/ui-library run build:prod emits dist/library-icons.json
• Example app picks up baseline (verified via plugin debug log)

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.73%. Comparing base (7bc9bb8) to head (41038be).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/ui-library/src/vite-plugin/index.ts	0.00%	10 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #523      +/-   ##
==========================================
- Coverage   84.89%   84.73%   -0.17%     
==========================================
  Files         143      143              
  Lines        5217     5227      +10     
  Branches     1554     1556       +2     
==========================================
  Hits         4429     4429              
- Misses        788      798      +10     

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