refactor(desktop): extract Session Navigation feature slice

[chihumyum]

Summary

• Extract Session rail projection, layout persistence, navigation intents, and row-mutation lifecycle into features/session-navigation.
• Add a narrow Desktop services adapter, feature host/controller, and architecture tests while preserving existing routes, storage keys, revision-family semantics, and UI behavior.

Refs #3439

Verification

• npm ci
• npm run check:asf-headers
• npm run lint
• npm run format:check
• npm run typecheck
• npm run build
• npm run astryx:theme -- --check
• npm run astryx:surface-inventory
• Desktop tests: 1419 passed
• Desktop and UI Knip checks passed
• Storybook build and render smoke: 189 stories passed
• Electron E2E: 62 passed, 1 conditionally skipped
• Browser observe/act smoke: 17/17 passed
• Astryx alignment audit: all fixtures clean
• git merge-tree --write-tree upstream/main HEAD

Review focus

Session catalog authority remains in the existing AppShell session-list boundary. The feature owns rail/view/mutation behavior; AppShell keeps explicit cross-feature intents.

AI use

Select exactly one:

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

Tool(s) and scope: Codex implemented the renderer feature extraction, tests, and red/blue review under human direction.

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

[Astro-Han]

Approving on eff7627bdcb336d973125cf8ed1417d908c6fe32, with test terminal green on that exact head.

For a move of this size the only question worth answering is whether anything changed semantics under cover of changing location, so I checked it mechanically rather than by reading. Comparing each moved file against its original with the licence header stripped:

• session-rail.ts, session-revisions.ts, session-nav-filter.ts, branch-banner.ts — byte-identical.
• session-list-layout.ts and session-project-grouping.ts — import paths only.
• session-row-actions.ts — the one file with real edits, and every one is mechanical: window.maka.sessions.* becomes the injected service.*, and setMessages([]) becomes clearActiveMessages(), which app-shell.tsx:1660 defines as useCallback(() => setMessages([]), [setMessages]). The revisionFamily semantics, the requireArchived and restored branches, the pending de-duplication, and the list read-back verification are all unchanged.

The three persisted layout keys and the 200 ms trailing debounce moved without modification, and openSession keeps its original ordering — exit WorkHub, select, activate, then set or clear the scroll target — including the suppression of activeId while WorkHub is active.

One incidental fix worth calling out in the description. deriveBranchBanner's memo dependencies were [activeSession?.parentSessionId, sessions] and are now [activeSession, sessions]. The old list was incomplete: switching between two sessions that share a parentSessionId did not recompute, so the banner could keep showing the previous parent's name after it changed. The new list is correct. That is a behaviour change — a fix, not a regression — and it should be mentioned rather than left inside a refactor.

The boundary is clean: no imports of app-shell, preload or main from inside the feature, the Desktop bridge is touched only in platform/desktop/create-session-navigation-services.ts, and the new boundary tests pin the "external code enters through index/testing only" rule rather than leaving it as a convention.

On merge order, not a blocker: this PR rewrites large parts of app-shell.tsx and deletes six files from the renderer root. Two sibling slice extractions are open against the same code. Whichever lands first will force the others to redo path-level work, so they should go in one at a time with a rebase between, rather than in parallel.

简体中文

已在 eff7627bdcb336d973125cf8ed1417d908c6fe32 上 approve，该 exact head 的 test 为终态绿。

这种规模的搬运，唯一值得回答的问题是「有没有借着换位置改语义」，所以我用机械方式核对，而不是靠通读。把每个被移动的文件与其原文件在剥掉 licence 头后逐一比对：

• session-rail.ts、session-revisions.ts、session-nav-filter.ts、branch-banner.ts——逐字节相同。
• session-list-layout.ts 与 session-project-grouping.ts——只改了 import 路径。
• session-row-actions.ts——唯一有实际改动的文件，而每一处都是机械的：window.maka.sessions.* 换成注入的 service.*；setMessages([]) 换成 clearActiveMessages()，后者在 app-shell.tsx:1660 定义为 useCallback(() => setMessages([]), [setMessages])。revisionFamily 语义、requireArchived 与 restored 分支、pending 去重、list 回读校验，全部未变。

三个持久化布局键与 200 ms trailing debounce 原样搬入；openSession 保持原有顺序——退出 WorkHub、选中、激活、再设置或清除 scroll target——包括 WorkHub 激活时对 activeId 的抑制。

有一处顺带的修复，建议写进正文。 deriveBranchBanner 的 memo 依赖由 [activeSession?.parentSessionId, sessions] 改为 [activeSession, sessions]。旧的依赖列表是不完整的：在两个共享同一 parentSessionId 的 session 之间切换时不会重算，因此父级名称变化后横幅可能仍显示旧名字。新的依赖是对的。这是一处行为变化——是修复而非回归——应当明说，而不是留在重构里。

边界是干净的：feature 内部没有对 app-shell、preload、main 的导入；Desktop bridge 只在 platform/desktop/create-session-navigation-services.ts 触碰；新增的边界测试把「外部只能经 index/testing 进入」这条规则用机器锁住，而不是留作约定。

关于合并顺序，不构成阻塞：本 PR 重写了 app-shell.tsx 的大段内容，并删除了 renderer 根目录下的六个文件。另有两个同类切片 PR 正对着同一片代码开着。谁先合，都会迫使其余两个重做路径级的调整，因此应当串行合并、中间让作者 rebase，而不是并行推进。