Publish searchable provider icon catalog

[konojunya]

Summary

• publish a searchable, filterable metadata catalog for 1,051 user-imported AWS, Google Cloud, Azure, and curated tool icons without hosting vendor SVG assets
• document local pack creation, browser-only import, offline CLI rendering, rights boundaries, and complete IDs in all four locales
• upgrade to @stack-sh/engine@0.6.0 and preserve every source archive plus per-icon brand provenance in Playground displays and exported notices
• keep large local packs usable with catalog search and bounded icon batches

This supersedes #14, which GitHub closed automatically when its stacked base branch was deleted after #13 merged.

Verification

• npm ci
• npm run format:check
• npm run lint
• npm test (19 tests)
• npm run build (48 documentation pages)
• npm run cloudflare:check
• npm audit --audit-level=high (0 vulnerabilities)
• local browser import, render, and NOTICE download with a schema 1.1 multi-source pack
• provider catalog search for Notion and all 45 Google Cloud records
• 390 px responsive check with no page overflow
• axe WCAG A/AA: 0 violations in Playground and provider documentation
• browser console: no errors