feat(IMP-11): D-2 — frame min_height_px hint (backend → UI)

Step 9 v4_all_judgments[] now exposes per-candidate min_height_px from
catalog frame_contracts.visual_hints.min_height_px (None when contract
unregistered). SlideCanvas pendingLayout zones render a red ring + 'min H
Npx' badge when zone height falls below the active frame's threshold.
Visual hint only; resize clamp (minSize=0.05) unchanged.

5 axes (single commit per Stage 5 plan):
- u1 backend: src/phase_z2_pipeline.py — Step 9 builder adds min_height_px
  via single get_contract(c.template_id) lookup; reuses _contract for
  catalog_registered (no double-lookup).
- u2 type: Front/client/src/types/designAgent.ts — FrameCandidate gains
  optional minHeightPx?: number.
- u3 mapper: Front/client/src/services/designAgentApi.ts — maps snake-case
  min_height_px → camelCase minHeightPx on v4_all_judgments path;
  v4_candidates fallback remains undefined (graceful).
- u4 active-frame lookup: Front/client/src/components/SlideCanvas.tsx —
  activeFrameId = overrideFrameId ?? defaultFrameId; activeCandidate via
  region.frame_candidates.find.
- u5 hint render: Front/client/src/components/SlideCanvas.tsx —
  zoneHeightPx = height * SLIDE_H (logical px, no double-apply); compare
  against activeCandidate.minHeightPx in pendingLayout mode only; red
  border + badge when below.

Tests: 5/5 pass in tests/test_phase_z2_step9_v4_all_judgments_min_height.py
(source-string + catalog-shape guards + None propagation, registered and
unregistered template_ids).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/phase_z2_pipeline.py

@@ -3969,6 +3969,24 @@ def run_phase_z2_mvp1(
                 "delegated_to": delegated,
             })
 
+        # IMP-11 D-2 (u1) — per-candidate min_height_px source = catalog
+        # frame_contracts[template_id].visual_hints.min_height_px (logical 1280×720 px).
+        # None when contract unregistered (frontend tolerates undefined).
+        # Single get_contract lookup binds both catalog_registered and min_height_px.
+        v4_all_judgments_list = []
+        for c in v4_all_for_unit:
+            _contract = get_contract(c.template_id)
+            v4_all_judgments_list.append({
+                "template_id": c.template_id,
+                "frame_id": c.frame_id,
+                "frame_number": c.frame_number,
+                "v4_rank": c.v4_rank,
+                "confidence": c.confidence,
+                "label": c.label,
+                "catalog_registered": _contract is not None,
+                "min_height_px": (_contract or {}).get("visual_hints", {}).get("min_height_px"),
+            })
+
         application_plan_units.append({
             "unit_id": unit_id,
             "layout_preset": layout_preset,
@@ -4004,18 +4022,8 @@ def run_phase_z2_mvp1(
             # v4_all_judgments 는 reject 포함.
             # catalog_registered = frame_contracts.yaml 에 contract 있는지 여부.
             # false 면 사용자가 override 시도해도 Step 7-A 가 skip (render path 미연결).
-            "v4_all_judgments": [
-                {
-                    "template_id": c.template_id,
-                    "frame_id": c.frame_id,
-                    "frame_number": c.frame_number,
-                    "v4_rank": c.v4_rank,
-                    "confidence": c.confidence,
-                    "label": c.label,
-                    "catalog_registered": get_contract(c.template_id) is not None,
-                }
-                for c in v4_all_for_unit
-            ],
+            # IMP-11 D-2 (u1) : per-candidate min_height_px added (None when unregistered).
+            "v4_all_judgments": v4_all_judgments_list,
             "application_candidates": app_candidates,
             # IMP-06 blocker-fix (Codex #13 Blocker 3 / #16) — plan-aware
             # additive fields. None / False / [] when no override CLI used.