feat(workspaces): prototype the panel components on the UI tree

[EhabY]

Prototype for DEVEX-621 on top of the Tree suite (#1065): the Workspaces panel rendered in the experimental coder.workspacesPanel test webview with mock data, so the row/panel components can be exercised before the real IPC wiring lands.

What's in the MVP

• WorkspacesPanel — toolbar + tree + state panels; owns the filter/search state. No IPC yet.
• WorkspaceFilterSelect — Mine / All / Shared radio menu on a secondary Button; Shared gated by isOwner.
• Workspace and agent rows as rich Tree labels with status StatusPills and hover-revealed inline actions (open/dashboard/settings; terminal/logs).
• Inline App Statuses and Agent Metadata sections under agents; metadata values carry a collected-at Tooltip.
• Live-filter SearchInput, plus LoadingState / ErrorState / EmptyState branches.
• Mock data lives in mockData.ts (local fixtures; @repo/mocks is lint-restricted from runtime code).

Notes

• @repo/ui becomes a webview dependency — this webview is its first production bundler. The shared Vite config aliases its TypeScript source and #cx/#codicons subpath imports; index.css imports the UI codicon stylesheet and tokens (theme-matched via --vscode-*).
• Intentionally out of scope: useWorkspaceData/IPC, Storybook stories, welcome/auth states, keyboard-nav acceptance tests — all belong to the full DEVEX-621 implementation.

Validation

• pnpm typecheck, pnpm lint, pnpm format:check
• pnpm build (all webviews + extension)
• pnpm test:webview — 46 files, 388 tests passed (incl. new WorkspacesPanel.test.tsx)
• pnpm test:extension — 119 files, 2098 tests passed

Implementation plan

Decisions (confirmed)

• Base branch: feat/ui-tree-suite (PR feat(ui): add accessible VS Code-parity Tree #1065).
• Target: packages/workspaces (coder.workspacesPanel), whose App.tsx was a TODO placeholder.
• Scope: tree + toolbar + rows + minimal loading/error/empty states.
• Draft PR on top of feat/ui-tree-suite.

Changes

Wiring

• packages/workspaces: add @repo/ui dependency; add @repo/ui tsconfig path; index.css imports codicon/tokens CSS; index.tsx wraps in TooltipProvider.
• packages/webview-shared/createWebviewConfig.ts: alias @repo/ui source and its package-internal subpath imports for bundlers.
• vitest.config.mts + test/tsconfig.json: @repo/workspaces path for tests.

Prototype components (packages/workspaces/src/)

• mockData.ts — local SDK-typed fixtures (own/shared/other-owner workspaces, agents with apps/statuses/metadata).
• WorkspacesPanel.tsx — top level; filter/search state, mock→TreeNode[] mapping, toolbar + Tree (sticky scroll) + state panels.
• WorkspaceFilterSelect.tsx — Mine / All / Shared radio menu.
• rows.tsx — workspaceNode / agentNode / appStatusSection / metadataSection builders with rich labels, pills, and hover actions.
• WorkspacesPanel.css — toolbar/tree layout.

Tests

• test/webview/workspaces/WorkspacesPanel.test.tsx — tree rendering, filter select, live search, empty/loading/error states, inline sections, hover actions.

Not in scope (MVP)

• Real IPC / useWorkspaceData / handler wiring.
• Storybook stories, pixel snapshots, keyboard-nav acceptance tests.
• Welcome/auth states, real command execution behind inline actions.

_{This pull request was created by Coder Agents on behalf of @EhabY.}

[linear-code]

DEVEX-621