fix(loop): address planner and reviewer architecture defects

- Fix B-1: Correct Mermaid sequence diagram syntax (fi -> end) in SKILL.md and PLAN_LOOP.md
- Fix B-2: Force target agent exclusion from active reviewers in run_loop.sh and correct creator session role in registry
- Fix B-3 & B-4: Integrate WAIT_TIMEOUT deadline inside wait_for_job
- Fix M-3: Update CHANGES_DIFF to use dynamic cumulative git diff
- Fix M-2: Resolve verdict string parsing and substring collisions

.agents/skills/multi-agent-mux-loop/SKILL.md

@@ -38,7 +38,7 @@ sequenceDiagram
         end
     else Self-Planning
         Loop->>Dev: notify direct task execution (Self-planned)
-    fi
+    end
     
     Loop->>Dev: delegate code implementation
     Dev-->>Loop: code modification complete