docs(fb-42): wire schema + README + SMOKE + design + SKILL + INDEX

- Add bulk_search_item.v1 + bulk_search_response.v1 wire schemas
- Register both in WIRE_SCHEMAS const
- README: --bulk flag mention + MCP tool list 7→8 (bulk_search)
- SMOKE: bulk multi-query walkthrough (CLI + MCP equivalent)
- Design §2.2: Bulk multi-query (fb-42) subsection (additive minor)
- SKILL: mcp__kebab__bulk_search section + tool table row
- Task spec status open→completed, banner replaced
- INDEX: fb-42 row 머지 (rerank hint deferred)
- Fix: missed Capabilities {bulk_search} in cli wire.rs test (Task 7 leftover)
- Fix: missed tools.len() 7→8 in cli_mcp_smoke (Task 5 leftover)

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

docs/superpowers/specs/2026-04-27-kebab-final-form-design.md

@@ -245,6 +245,12 @@ normalize: rrf_score = raw_rrf / (2 / (k_rrf + 1))
 
 `score_kind` 는 wire schema v1 에 **optional** 필드로 추가 (additive, backwards-compat). 누락 시 historical default `rrf` 로 해석.
 
+#### Bulk multi-query (fb-42)
+
+`kebab search --bulk` (stdin ndjson) + `mcp__kebab__bulk_search` tool 신규. agent 가 N sub-query 한 번에 실행 — query decomposition 시 단일 round-trip. Cap 100 per call. Sequential for-loop, App instance 재사용 → 캐시 / embedder cold-start 비용 한 번만.
+
+Per-query failure 는 `bulk_search_item.v1.error` (error.v1) 에 격리, 다른 query 계속 진행. wire shape additive minor (`bulk_search_item.v1` + `bulk_search_response.v1` 신규).
+
 ### 2.3 Answer
 
 ```json