feat(desktop): refresh Reasonix desktop UI

[GTC2080]

Summary

• Refresh the Reasonix desktop shell with the new dark/light adaptive UI, stable sidebar spacing, search dialog, settings center, plugin hub, workspace dock, and bottom terminal surface.
• Add real desktop bindings for the terminal session and keep plugin/skill management, MCP settings, archived chats, and project navigation connected to backend state.
• Add rendering/performance infrastructure: lazy surfaces, virtualized lists, stable event hooks, requestAnimationFrame throttling, markdown caching, and bundle/smoke performance scripts.

Design Evidence

• Refs [Feature]: Desktop UI refresh proposal for main-v2 #3805
• Screenshots and latest desktop UI proposal are attached in the linked issue.

Validation

• npm run check:css
• npm run test:all
• npm run typecheck
• npm run build
• npm run perf:bundle
• go test ./... from desktop
• go test ./internal/config -run TestSkillPathMutators

[SivanCola]

以后涉及ui的变动，最好是附图。纯代码合并风险有些高。

[GTC2080]

收到，确实应该把 UI 变更的视觉证据放得更明确一些。

这次 PR 的截图和完整桌面 UI 提案已经放在关联 issue #3805 中，PR 描述里的 Design Evidence 也链接到了该 issue：
#3805

[esengine]

Stepping back on this one rather than line-reviewing it: a +13k-line shell replacement can't be reviewed or landed as a unit, and several of its choices reverse things that shipped deliberately — it deletes AppChrome/CommandPalette/HistoryPanel/ContextPanel (we merged a palette fix of yours into that exact surface the same day), and swaps the accent identity. #3805 also hasn't had a direction discussion yet; a redesign this size needs sign-off on the proposal before code. The terminal dock additionally needs a real PTY design — the pipe-based session can't host interactive programs, and Process.Kill without a job object orphans children on Windows.

To be clear, this isn't a "no" to the ideas: VirtualList, useRafThrottle/useStableEvent, the markdown render caching, and the perf scripts would each be welcome as small standalone PRs today — the virtualization piece in particular addresses a known long-session slowdown. And if the #3805 discussion lands on a refresh direction, this branch is the reference implementation for it. Your recent fixes have been excellent; I'd rather take this work in pieces we can actually review than let it rot whole.

[GTC2080]

Acknowledged. I am leaving this branch as a reference implementation instead of continuing to ask for review as one large shell replacement.

First standalone split: #3990, which only virtualizes the existing History/Trash saved-session list and closes #3989.

I will keep the broader #3805 redesign in the proposal discussion path, and keep the terminal dock out until there is a real PTY/job-object design.