feat(design-system): add the full catalog and generated UI foundation

[mahanti]

A complete, portable design-system catalog

Buzz's /design now lays out the open-source foundation: 54 searchable live component examples, visual token specimens, light/dark modes, source examples, product compositions, and an adaptation guide. It consumes the shared packages directly and builds as a static site with local fonts and license notices, without a native shell or internal documentation host.

Adds a versioned generated-response schema and renderer for text, notices, metrics, tasks, tables, and actions. Inputs are bounded and validated; generated markup stays text; actions require a host allowlist and an explicit click. Streaming, pending, and invalid states retain visible feedback and recovery.

Browser integration also corrects essential-control contrast, number-field label wiring, avatar semantics, link-button semantics, and visible toast dismissal. Command results preserve their live announcement without an empty spacer. Dialog heading gaps are 16px, accordion rows are compact, toasts slide/fade, and tab indicators slide between selections with reduced-motion support. The Glass specimen uses the same tab component via a named glass variant. Native and custom scrollbars use a thin treatment, table cells align to the reading edge, and the 1rem resize grip retains a larger drag target. CI builds and tests the packages/catalog and uploads the static site as an artifact.

Stack 3 of 4: #7522 → #7523 → this PR. Base: codex/design-system-components. All remain draft. Next layer: #7533 (AI composer and compact card headers).

Validation:

• Production package and catalog builds, TypeScript declarations, formatting, and typography audit pass.
• Token generation, compiled utility mapping, both-mode APCA text contrast, and 3:1 essential-control contrast pass.
• 8 token/schema/renderer tests and all 22 Chromium tests pass, including spacing measurements, empty-state recovery, toast entrance/exit, interrupted tab transitions, Glass keyboard selection, table alignment, thin scrolling, pointer/keyboard resizing, zoom-relative grips, and reduced-motion behavior. Browser coverage includes both-mode axe checks, local-only runtime requests, keyboard interactions, modal focus return, forms, resize, generated actions/recovery, reduced motion, all foundation routes, and responsive widths of 390/768/1440px.
• Latest just ci passes the earlier formatting, lint, Rust unit, desktop JS, and desktop build stages, then stops in desktop-tauri-test: relay_admission::tests::gate_armed_by_one_path_withholds_another_path reports that a send ran before a 1-second gate elapsed (3163 tests passed, 1 failed, 19 ignored). The failing test passes when rerun individually. This change touches no relay-admission or Rust code; later repository-wide stages were not reached.

Scope: React/web foundation for desktop-next; existing desktop and Flutter clients are not migrated. The chart currently supports categorical bars and the carousel manual navigation. This is independently authored Buzz styling over public dependencies, not a private-source export or a promise of shadcn/BlockUI API compatibility. No npm package or public website is automatically published.

Run locally: pnpm --filter buzz-desktop-next dev, then open /design on port 1430. Full setup and hosting instructions: desktop-next/README.md.

Light, dark, and composition screenshots.

[mahanti]

🤖 Screenshots captured by the AI agent from the production catalog build.

Overview — light

The shared foundations and component treatments using locally bundled Inter and Lucide.

Overview — dark

The same components using the authored dark semantic roles.

Product and generated compositions

A project workspace, settings flow, and validated generated responses use the same library.