fix(loop): repair review-diff/verdict-parsing bugs, deduplicate session lookups

Applies the P0-P3 fixes from the multi-agent-mux-loop audit
(.mam/jobs/ab686e47/claude-reports/report-final.md):

- P0-1: capture BASE_COMMIT before Phase 2 and diff against it, so reviewer
  diffs stay non-empty and cumulative even after the Creator commits per the
  documented DoD (bare `git diff` alone showed nothing once committed).
- P0-2: has_verdict now matches only the report's last non-blank line, so a
  stray [VERDICT: ...] token quoted mid-report as a formatting example can no
  longer flip the outcome.
- P1-1: replace the English-only refactor/complex/design/architect keyword
  sniff (dead code against Korean-language reviewer reports) with an explicit
  [ESCALATE: PLANNER] tag the reviewer prompt now asks for.
- P1-2: resolve_all_reviewers/resolve_agent_type/resolve_planner_session now
  read through lib.sh's load_state_json single source of truth instead of
  each hand-rolling its own SQLite+YAML lookup; resolve_agent_type's name
  fallback matches exact hyphen segments instead of a substring `in` check.
- P2-1: warn when --all-reviewer and --reviewer are both given, since the
  latter is silently discarded.
- P2-2: correct the SKILL.md CLI-mapping table row that overstated an
  automated lint gate and an unconditional Planner feedback loop.
- P3: fix lib.sh shellcheck SC2164 (unguarded cd in start_watchdog) and
  annotate the intentional SC2317 dual source/exec guard.

Verified: shellcheck clean on both scripts, bash -n syntax OK, and the
rewritten has_verdict/resolve_* functions were unit-tested against this
repo's live .mam/agent-sessions state.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.agents/skills/lib.sh

@@ -16,6 +16,9 @@
 
 if [ -z "${BASH_VERSION:-}" ]; then
   echo "ERROR: lib.sh must be executed/sourced from bash (foreign shell detected)" >&2
+  # Reachable when this file is executed directly rather than sourced;
+  # `return` only fails (falling through to `exit`) in that path.
+  # shellcheck disable=SC2317
   return 1 2>/dev/null || exit 1
 fi
 SKILL_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
@@ -1018,10 +1021,10 @@ start_watchdog() {
     # Start the wildcard monitor subscriber daemon with --idle-timeout 0 (never idle out)
     # and ensure it runs with $workdir as cwd to anchor relative log paths.
     local orig_pwd="$PWD"
-    cd "$workdir"
+    cd "$workdir" || return 1
     nohup bash "$monitor_script" --subscribe --idle-timeout 0 >> "$log_file" 2>&1 &
     pid=$!
-    cd "$orig_pwd"
+    cd "$orig_pwd" || return 1
   fi
   
   echo "$pid"