feat(desktop): consume task submission readiness - #2523

Addressed all three suggestions in 4405412ce:

• Active-session readiness now consumes the existing sessionSendOutcome; an unlocked stale Session checks the projected rebind target, and model readiness does not override that authority while the projection is loading/ready/rebinding.
• Ordinary, Graph, and Swarm submissions perform a fresh readiness read immediately before the real send. Confirmed blockers stop; unknown remains fail-open. Concurrent reads are sequenced so stale responses cannot overwrite the latest result.
• Workspace recovery now follows the snapshot repairTarget. From an active Session it opens the new-task surface; when already there it opens workspace addition/selection instead of issuing a no-op “New task”.

Added the stale-session rebind behavior case; 18 targeted readiness tests, Desktop main build, and Renderer typecheck pass.

已在 4405412ce 处理三点：复用 session-send projection、每次真实发送前重新检查且 unknown 放行、并按 repairTarget 路由工作区恢复操作。

Thanks for addressing the previous round — I should have been more explicit about ownership in my send-time suggestion. The remaining issue is not the refresh itself, but keeping authorization and execution bound to the same submission target.

• P2: The readiness await currently runs before send() captures initialSessionId. If the user switches sessions while that read is pending, readiness is checked for session A, but the stable send facade can then submit the text and attachments to session B.

The smallest patch would be to capture the composer owner before the await and cancel if it changes. The cleaner fix, and my preference, is to move the readiness guard into createAppShellChatActions.send(), immediately after it captures initialSessionId / sendOwner, and remove the three call-site checks. That keeps capture → readiness → send under one owner and preserves the existing navigation semantics. A deferred-read regression that switches sessions before resolving would lock this down.

Fixed in de8f00830 using the preferred ownership boundary:

• createAppShellChatActions.send() now captures initialSessionId / composer owner first, then awaits the readiness guard, then verifies that the same owner is still active before any Session creation, turn arm, attachment ingest, or sessions.send.
• Removed the three ordinary / Graph / Swarm call-site checks; every path now goes through the single stable send guard.
• Added a deferred-read regression: readiness starts for Session A, navigation switches to Session B before resolution, and the send returns false with zero sessions.send calls.

22 related tests pass, along with Desktop main build and Renderer typecheck.

已在 de8f00830 将 readiness 检查绑定到稳定 send owner，并增加延迟读取期间切换 Session 的回归测试。