docs(plan): schedule the orphan tmux session client parity work

The server half shipped 2026-07-30 as feature A (4892fa7/f6ef19e/d39a0ab) and
both native clients are at zero. This is NOT a regression — OrphanSessionInfo is
deliberately a separate type rather than a flag on LiveSessionInfo, and
src/server.ts:600 names the reason: the clients decode /live-sessions, so a
variant shape there would have broken them.

It is worth planning anyway because SessionManager.shutdown only detaches the
tmux client for tmux-backed sessions (manager.ts:410-417), so a server restart
or a desktop-app quit turns every session into an orphan. The web launcher lists
them and re-adopts on tap; the phone still shows an empty list — which is the
walk-away case this product exists for.

The plan doc carries the eleven traps a client implementer will hit, each one a
shipped review finding or a documented server subtlety — notably that preview
returns cols/rows of literally 0 (both clients currently size thumbnails from
that response), that a 429 must not collapse to "no orphans", and that the
destructive confirmation must come from count-idle rather than card count (that
one nearly ended 33 shells while the dialog said 24).

Also corrects two now-false claims found while cross-referencing: the ROADMAP
row for tmux discovery was half-stale, and ANDROID_CLIENT_PLAN's do-not-consume
list still listed POST /projects/worktree (both clients consume it now) and
GET /sessions (iOS consumes it, Android does not — so "match iOS" now argues
for building it, not against).

docs/PLAN_IOS_CLIENT.md

@@ -598,6 +598,18 @@ W5 验收(report-only, 并行)
   Android instrumented 腿（`TinkAccessTokenStoreTest` 是令牌静态加密的唯一证明，需真机或模拟器，CI 上暂设为
   `workflow_dispatch` 触发——理由写在 `android.yml` 文件头：没人见它绿过的腿若设为必过，只会逼出一个假绿）。
 
+### 7.2 已排期未开工 —— 同样不新编 `T-iOS-*` 号
+
+- **`[ ]` 孤儿 tmux 会话（feature A 的客户端半边）** · **Effort: M** · 计划见
+  [`docs/plans/w7-orphan-session-clients.md`](./plans/w7-orphan-session-clients.md)。
+  服务端 2026-07-30 已上线五条路由（`4892fa7`/`f6ef19e`/`d39a0ab`），**iOS 与 Android 均为零接入**。
+  **不是回归**：`OrphanSessionInfo` 被刻意做成独立类型而非 `LiveSessionInfo` 上的 flag，`src/server.ts:600`
+  写明理由就是"两个原生客户端解码 `/live-sessions`，在那里加变体形状会破坏它们"——既有解码器不受影响。
+  **但值得做**：`SessionManager.shutdown` 对 tmux 会话只 `pty.kill()` 断开客户端、不杀 shell
+  （`src/session/manager.ts:410-417`），所以**服务器一重启 / 桌面 app 一退出，所有会话都变成孤儿**。
+  网页 launcher 已能列出并一键重新接管，**手机上却是一个空列表**——正是本项目"走开后从手机上看"的核心用例。
+  开工前须按 §7 的 P2 门槛先扩写 RED 清单（写进该计划文档的 `## RED test list` 节），未扩写不得分派。
+
 ### P0 — 每日可用（"口袋里能开终端、能批准"）· 合计 ~13 人天
 
 #### W0 · 基础（串行）