feat(ui): add Zaidan Storybook baseline

[kattsushi]

Part of tracker #2. Targets feat/ui-package.

Closes #1

PR Type

• Bug fix
• New feature
• Documentation only
• Code refactoring
• Maintenance/tooling
• Breaking change

Summary

• Adds the PR 2 Zaidan component baseline for @os-copilot/ui.
• Wires Storybook for Solid/Vite through Nx with mobile-first stories under packages/ui/src/stories/ui.
• Adds Tailwind v4/tw-animate CSS foundation and keeps chart/ECharts opt-in via subpath export.

Chain Context

master
└── 📍 tracker #2: feat/ui-package
    ├── ✅ PR #3: scaffold package + shadcn routing
    └── 🔎 PR #4: Zaidan baseline + Storybook/CSS

Changes

File	Change
packages/ui/src/components/ui/*	Adds Zaidan UI component batch and SSR-safe support hook.
packages/ui/src/stories/ui/*	Adds Storybook stories for the installed component baseline.
packages/ui/.storybook/*	Configures Storybook Solid/Vite with UI styles and mobile viewport defaults.
packages/ui/src/styles.css, packages/ui/src/styles/base.css	Adds Tailwind v4, Inter, neutral/Vega tokens, and animation utilities.
packages/ui/package.json, packages/ui/project.json, nx.json	Adds Storybook scripts, Nx targets/plugin, exports, and package dependencies.
pnpm-workspace.yaml, pnpm-lock.yaml	Centralizes new dependency versions in the workspace catalog.
.gitignore	Ignores Storybook static output.

Test Plan

• pnpm exec dprint check
• pnpm exec oxlint
• pnpm nx typecheck ui
• pnpm nx build ui
• pnpm nx test ui --run
• pnpm nx build-storybook ui
• pnpm nx typecheck web
• Fresh reviewer audit completed with no blockers.

Notes

• Storybook emits a non-blocking warning: unable to find package.json for @kobalte/core. This comes from Kobalte not exporting ./package.json in its package exports.
• The chart story intentionally pulls ECharts and causes a large Storybook chunk; chart is not exported from the root package entry and remains opt-in.

Contributor Checklist

• Linked an approved issue
• Added exactly one type:* label
• Ran shellcheck on modified scripts (not applicable: no shell scripts changed)
• Skills tested in at least one agent
• Docs updated if behavior changed
• Conventional commit format
• No Co-Authored-By trailers