feat(#67): IMP-38 V4 max_rank policy formalization (u1~u3, 4 round consensus)

- u1: separate templates/phase_z2/catalog/v4_fallback_policy.yaml + load_v4_fallback_policy() loader
  (catalog pollution prevention — Codex #1 correction)
- u2: dynamic effective max_rank in lookup_v4_match_with_fallback (3-variable ceiling min,
  Codex #2 correction: min(configured, len(judgments_full32))) + 3-tier usable predicate
  (status + catalog + optional capacity) + trace 8 fields (requested/default/configured_extended/
  judgments_count/effective_extended_ceiling/effective_max_rank/usable_count/policy_applied)
- u3: 2 production call site cleanup (max_rank=3 removed, HEAD baseline) + tracked
  Front/vite.config.ts PHASE_Z_MAX_RANK env retired + 4 regression scenarios

verified: 32 passed (IMP-38 focused scope) — IMP-05 L4 dedup / L2 schema preserved,
IMP-30 allow_provisional byte-identical, caller_override backward compat (tests)

Stage cycle (#67, 7 round Claude + 5 round Codex):
- Stage 1: Claude #1 -> Codex #1 YES + 5 corrections
- Stage 2 r1+r2: Claude #2-#4 -> Codex #2 Q2 -> Codex #3 YES (4 round consensus LOCK 23195)
- Stage 3 U1+U2+U3: Claude #5-#9 -> Codex #6 NO 4to3 correction -> Codex #7 YES -> Codex #8 YES
- Stage 4: Claude #11 -> Codex #9 (anchor attribution nuance) -> Codex #10 readiness -> Codex #11

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Front/vite.config.ts

@@ -346,8 +346,10 @@ function vitePluginPhaseZApi(): Plugin {
           const pythonExe = process.platform === "win32" ? "python.exe" : "python";
           // 2026-05-14 — env toggle forward (보고용 일회성).
           //   PHASE_Z_ALLOW_RESTRUCTURE / PHASE_Z_ALLOW_REJECT : status 통과
-          //   PHASE_Z_MAX_RANK=32 : V4 fallback chain 의 max_rank 확대 (등록 frame 까지 검색)
-          // 04-1 (all reject) / 05-2 (rank 1~3 미등록) 등 자동 매칭 가능.
+          // 2026-05-21 — IMP-38 retire PHASE_Z_MAX_RANK env (never read by backend).
+          //   v4 fallback chain max_rank 는 templates/phase_z2/catalog/v4_fallback_policy.yaml 의
+          //   정식 정책 (dynamic_usable_count_based) 으로 결정 — backend src/phase_z2_pipeline.py
+          //   의 lookup_v4_match_with_fallback() 가 load_v4_fallback_policy() 로 적용.
           const proc = spawn(pythonExe, cliArgs, {
             cwd: DESIGN_AGENT_ROOT,
             shell: false,
@@ -355,7 +357,6 @@ function vitePluginPhaseZApi(): Plugin {
               ...process.env,
               PHASE_Z_ALLOW_RESTRUCTURE: "1",
               PHASE_Z_ALLOW_REJECT: "1",
-              PHASE_Z_MAX_RANK: "32",
             },
           });