fix(issue-42): review R1 - stop's exit 1 also comes after the stop

The registry update after the kill chain raises SystemExit(1) when the row
disappeared during the run (stop_session.sh:310), so "exit 1 changed nothing"
was false on that path. The stop table now says so, the code is declared as a
passthrough, and the test requires every integer SystemExit in an entry
script's heredocs to be declared - the check that would have caught it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/data/skill_code_blocks.json

@@ -593,7 +593,9 @@
     "4",
     "other"
    ],
-   "passthrough": {}
+   "passthrough": {
+    "1": "multi-agent-mux-stop/scripts/stop_session.sh:310"
+   }
   },
   "multi-agent-mux-create/scripts/create_session.sh": {
    "skill": "multi-agent-mux-create",
@@ -616,6 +618,7 @@
   "C4: create named a nonexistent `agent-sessions-yaml-edit` script; removed (create_session.sh writes the row)",
   "C5: create's cmd_full table (claude = `claude`) disagreed with adapter spawn-spec; replaced by \"decided by spawn-spec\"",
   "C6: create_session.sh header lists exit 4 \"YAML append failure\"; there is no literal `exit 4`, but the YAML write raises SystemExit(4) for a duplicate running row (create_session.sh:515) and it passes through, so 4 IS a real exit code (the plan assumed it was not)",
-  "R6: resume's \"The script above re-passes them\" and \"as done in Workflow above\" pointed at the removed block; reworded (same for create's Verification note)"
+  "R6: resume's \"The script above re-passes them\" and \"as done in Workflow above\" pointed at the removed block; reworded (same for create's Verification note)",
+  "R7 (review 08e1f1b2): stop's table said exit 1 is always pre-stop; the registry update after the kill chain also raises SystemExit(1) (stop_session.sh:310) when the row disappeared"
  ]
 }