feat(IMP-17): AI repair fallback infra carve-out — design-only boundary + 3-cond AND gate

u1 — src/phase_z2_pipeline.py:564 route hint comment corrected from
non-existent IMP-31 to IMP-17 (carve-out, AI fallback only, normal path 밖).
Line 565 IMP-29 frontend override reference untouched.

u2 — docs/architecture/IMP-17-CARVE-OUT.md (new) defines:
- allowed scope (Step 12 restructure proposal, Step 16/17 retry fallback)
- forbidden scope (normal-path AI calls, MDX compression, HTML structure)
- 3-condition AND activation gate (User GO ∧ B4 frame_selection evidence
  ∧ IMP-04 catalog + IMP-05 V4 fallback live)
- pattern shape reference (link-only): content_editor.py:21,318 +
  sse_utils.py:16-50 (Phase Q Archive Candidate, no port)
- AI 격리 contract + Kei persona 단절 (permanent)

u3 — PHASE-Z-IMPLEMENTATION-ISSUE-BACKLOG.md:68 IMP-17 row gains
carve-out doc link + 3-cond AND gate pointer.

u4 — PHASE-Q-INSIGHT-TO-22STEP-MAP.md AI repair fallback infra registry
row prefixed with IMP-17 + carve-out link; normal_path=no preserved.

Anchor test: tests/orchestrator_unit/test_imp17_comment_anchor.py asserts
line 564 IMP-17 wording AND line 565 IMP-29 preservation (2 tests pass).

Runtime behavior change: 0. Only delta in executable file is one comment
line. Normal-path AI invocation count remains 0.

Refs: gitea #17

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

docs/architecture/PHASE-Q-INSIGHT-TO-22STEP-MAP.md

@@ -120,7 +120,7 @@
 | A-4 slide-base iframe mode | Step 13 | §2.8 I2 (renderer.py slide-base 사용 호출 지점) | pending | yes (UI/backend) |
 | Step 14 visual_check 보강 | Step 14, 21 | §2.7 H1 (`content_verifier` utilities Reference Only) | pending | yes (deterministic) |
 | B-2 verification 보조 | Step 1, 2, 14, 21, 22 | §2.7 H3 (text 추출 / 정규화 / 비교 utility) | pending | yes (UI/backend) |
-| AI repair fallback infra | Step 12, 16, 17 | §2.6 G3 (`httpx` + SSE streaming + retry + JSON parse pattern) | pending | no (AI fallback only) |
+| IMP-17 AI repair fallback infra (carve-out — see [`IMP-17-CARVE-OUT.md`](IMP-17-CARVE-OUT.md)) | Step 12, 16, 17 | §2.6 G3 (`httpx` + SSE streaming + retry + JSON parse pattern) | pending | no (AI fallback only) |
 | I3 SVG 좌표 보강 | Step 0, 9 | §2.8 I3 (`renderer._preprocess_svg_data`) | pending | yes (deterministic) |
 | I4 zone 비중 분배 | Step 8 | §2.8 I4 (`renderer._group_blocks_by_area`) | pending | yes (deterministic) |
 | H2 frame contract validation | Step 10 | §2.7 H2 (`content_verifier.verify_structure` pattern) | pending | yes (deterministic) |