Ignore orphan app-server responses during turn waits

[yvette-carlisle]

Summary

• tolerate recorded orphan JSON-RPC responses while waiting for turn completion
• keep orphan JSON-RPC errors fail-closed
• add a fake app-server regression covering a late response followed by turn completion

Verification

• cargo make check

Runtime note

• installed locally with cargo install --path apps/decodex --force before this PR so the active ProfitPilot/PubFi intake could continue.

[yvette-carlisle]

Closing this as superseded by main.

Triage notes:

• The three PR commits are patch-equivalent to commits already on main: 480551a (turn waits), e07fad2 (request waits), and 26c4c94 (structured app-server error notifications).
• That work was later reconciled and landed through e12f4b1 / e519c3b for XY-531.
• The PR branch is now 41 commits behind main, mergeable=false, and a merge-tree check reports conflicts in the same app-server protocol files.

No remaining value in keeping this PR open; reopening or merging it would only reintroduce stale-branch risk.