Close the Minor-severity escape hatch

With merged review, a planted verbatim-duplication defect shipped: the
reviewer rated it Minor (YAGNI) under the strict cannot-be-trusted
definition of Important, and the Minor-rolls-up rule meant no fix was
ever dispatched and the final review never saw the finding. Calibration
now names merge-blocking maintainability damage (verbatim duplication,
swallowed errors, assertion-free tests) as Important, and controllers
must paste accumulated Minor findings into the final review dispatch.

skills/subagent-driven-development/SKILL.md

@@ -158,7 +158,9 @@ final whole-branch review. When you fill a reviewer template:
   lines). A reviewer with the diff in hand needs few or no tool calls; do
   not make reviewers re-derive the diff.
 - Dispatch fix subagents for Critical and Important findings. Record Minor
-  findings and move on — they roll up to the final whole-branch review.
+  findings and move on — then paste the accumulated Minor findings into the
+  final whole-branch review dispatch so it can triage which must be fixed
+  before merge. A roll-up nobody reads is a silent discard.
 
 ## Prompt Templates
 

skills/subagent-driven-development/task-reviewer-prompt.md

@@ -104,8 +104,11 @@ Subagent (general-purpose):
     ## Calibration
 
     Categorize issues by actual severity. Not everything is Critical.
-    Important means this task cannot be trusted until it is fixed;
-    "coverage could be broader" and polish suggestions are Minor.
+    Important means this task cannot be trusted until it is fixed: incorrect
+    or fragile behavior, a missed requirement, or maintainability damage you
+    would block a merge over — verbatim duplication of a logic block,
+    swallowed errors, tests that assert nothing. "Coverage could be broader"
+    and polish suggestions are Minor.
     Acknowledge what was done well before listing issues — accurate praise
     helps the implementer trust the rest of the feedback.