feat(desktop): separate Git review empty and error states

[Colafornia]

English

Summary

A valid non-Git task directory used to render the same red error Banner with Retry as a genuine read failure, even though retrying can never turn a directory into a repository. The Changes panel now classifies GitReviewReadResult failures: not_git_repository, workspace_unavailable, unborn_repository and remote_workspace are capability states that get neutral guidance naming the task's recorded workspace, while git_failed keeps an error Banner with the underlying detail and a working Retry. A clean repository with no differences still takes the separate "no changes" empty state.

The capability guidance offers "Change task folder", which reuses the existing Task Entry session workspace recovery picker (#5551), reached through a small application/contracts publish/subscribe seam rather than a shell-drilled prop so AppShell's debt metrics stay flat, so relocation preserves task identity instead of offering a new-task or default-directory action. A catalog-level subscribeSessionChanges subscription re-reads the Session's actual workspace after relocation, so the panel refreshes without a manual retry.

Fixes #5940

Verification

• npm run lint, npm run format:check, npm run build, npm run typecheck, npx knip --workspace apps/desktop, npx knip --workspace packages/ui: all pass.
• npm --workspace @maka/core run test:dist: 915/915 pass.
• npm --workspace @maka/desktop run test:dist: 3261/3261 pass, including new coverage: non-Git guidance with the task directory and no Retry, unavailable-workspace guidance with Retry plus the recovery action, unborn-repository guidance, git_failed detail preserved through redaction with a working Retry, a remote host-owned workspace showing guidance with neither Retry nor recovery, and a session catalog change re-reading the relocated workspace. Four new IPC tests assert the recorded workspace is attached for non-Git and missing directories, and that an unknown Session is rejected.
• npm --workspace @maka/desktop run build-storybook + npm --workspace @maka/desktop run smoke:storybook: all 455 stories render; ChangesSourceNotGit, ChangesWorkspaceUnavailable, ChangesUnbornRepository, ChangesRemoteWorkspace and ChangesGitReadFailed cover the new states.
• Manual, dev build: non-Git guidance shows the task path with no Retry; moving a task's folder away produces the unavailable guidance; relocating through the recovery action refreshes the panel to the new workspace.

Not run: the full Electron E2E suite (npm run e2e).

Screenshots (storybook capture):

State	Light	Dark
Not a Git repository
Workspace unavailable
Workspace managed by a remote Runtime Host
Git read failed
Unborn repository
No changes (empty)

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Devin (Cognition) implemented the change end to end — result contract fields, main-process read and IPC, panel rendering and copy, recovery plumbing, tests and stories. Generated-by trailers are on the commits.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No

中文

Summary

此前，一个合法但非 Git 的任务目录会渲染与真实读取失败相同的红色错误 Banner 和"重试"按钮，尽管重试不可能把目录变成仓库。现在变更面板按 GitReviewReadResult 的失败原因分类：not_git_repository、workspace_unavailable、unborn_repository 和 remote_workspace 属于能力态，展示中性引导并标注任务记录的工作区路径；git_failed 保持错误 Banner，附带底层错误 detail 和有效的"重试"。干净的仓库仍走独立的"无变更"空态。

能力态引导提供"更改任务目录"动作，复用 Task Entry 既有的会话工作区恢复选择器（#5551），该命令经 application/contracts 发布/订阅 seam 获取、不经 shell prop 下钻，AppShell 债务指标保持不变；迁移保留任务身份，而不是提供新任务或默认目录动作。新增的 catalog 级 subscribeSessionChanges 订阅在迁移完成后重新读取 Session 的实际工作区，面板无需手动重试即刷新。

Fixes #5940

Verification

• npm run lint、npm run format:check、npm run build、npm run typecheck、npx knip --workspace apps/desktop、npx knip --workspace packages/ui：全部通过。
• npm --workspace @maka/core run test:dist：915/915 通过。
• npm --workspace @maka/desktop run test:dist：3261/3261 通过，含新增覆盖：非 Git 引导显示任务目录且无重试；目录不可用引导含重试与恢复动作；零提交仓库引导；git_failed 经脱敏保留 detail 且重试有效；远程 Runtime Host 管理的工作区只显示引导、无重试与恢复动作；会话 catalog 变更触发对迁移后工作区的重读。另有 4 个新 IPC 测试断言非 Git 与缺失目录附带记录的工作区路径，以及未知 Session 被拒绝。
• npm --workspace @maka/desktop run build-storybook + npm --workspace @maka/desktop run smoke:storybook：455 个 story 全部渲染；ChangesSourceNotGit、ChangesWorkspaceUnavailable、ChangesUnbornRepository、ChangesRemoteWorkspace、ChangesGitReadFailed 覆盖新状态。
• 手工（dev 构建）：非 Git 引导显示任务路径且无重试；移走任务目录后显示不可用引导；经恢复动作迁移后面板自动刷新到新工作区。

未运行：完整 Electron E2E(npm run e2e)。

截图(storybook capture):

状态	浅色	深色
非 Git 目录
目录不可用
远程 Runtime Host 管理的工作区
Git 读取失败
零提交仓库
无变更

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope：Devin（Cognition）端到端实现了本次改动 —— 结果契约字段、主进程读取与 IPC、面板渲染与文案、恢复链路、测试与 story。提交含 Generated-by trailer。

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — described under Summary above
• No