refactor(rename): kb crates → kebab — Cargo packages, folders, Rust modules

프로젝트 이름 `kb` → `kebab` rename 의 첫 단계.

- workspace `Cargo.toml`: members `crates/kb-*` → `crates/kebab-*`,
  repository URL `altair823/kb` → `altair823/kebab`.
- 18 crate 폴더 rename via `git mv` (history 보존).
- 각 crate `Cargo.toml`: `name = "kb-*"` → `"kebab-*"`, path deps
  `../kb-*` → `../kebab-*`.
- 모든 `.rs`: `kb_<id>` snake-case 모듈 path 18 개 (`kb_core`,
  `kb_config`, `kb_app`, `kb_cli`, `kb_eval`, `kb_search`, `kb_chunk`,
  `kb_normalize`, `kb_source_fs`, `kb_parse_md`, `kb_parse_types`,
  `kb_store_sqlite`, `kb_store_vector`, `kb_embed`, `kb_embed_local`,
  `kb_llm`, `kb_llm_local`, `kb_rag`) → `kebab_<id>` 일괄 sed (단어
  경계 \\b 사용해 영어 문장 안의 "kb" 약어 미오염).

CLI binary 이름 (`[[bin]] name = "kb"`), 환경변수 `KB_*`, XDG paths,
tracing target, 그리고 docs sweep 은 다음 commit 에서.

## 검증

- `cargo check --workspace` clean — 모든 crate 빌드 통과 후 commit.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

crates/kebab-search/tests/fixtures/search/hybrid/run-1.json

@@ -0,0 +1,42 @@
+[
+  {
+    "chunk_id": "c1000000000000000000000000000000",
+    "fusion_score_positive": true,
+    "lex_some": true,
+    "lexical_rank": 1,
+    "method": "hybrid",
+    "rank": 1,
+    "vec_some": true,
+    "vector_rank": 3
+  },
+  {
+    "chunk_id": "c2000000000000000000000000000000",
+    "fusion_score_positive": true,
+    "lex_some": true,
+    "lexical_rank": 2,
+    "method": "hybrid",
+    "rank": 2,
+    "vec_some": true,
+    "vector_rank": 2
+  },
+  {
+    "chunk_id": "c4000000000000000000000000000000",
+    "fusion_score_positive": true,
+    "lex_some": false,
+    "lexical_rank": null,
+    "method": "hybrid",
+    "rank": 3,
+    "vec_some": true,
+    "vector_rank": 1
+  },
+  {
+    "chunk_id": "c3000000000000000000000000000000",
+    "fusion_score_positive": true,
+    "lex_some": false,
+    "lexical_rank": null,
+    "method": "hybrid",
+    "rank": 4,
+    "vec_some": true,
+    "vector_rank": 4
+  }
+]

crates/kebab-search/tests/fixtures/search/lexical/run-1.json

@@ -0,0 +1,60 @@
+[
+  {
+    "chunk_id": "c3000000000000000000000000000000",
+    "chunker_version": "v1",
+    "citation": {
+      "end": 8,
+      "kind": "line",
+      "path": "notes/snap.md",
+      "section": "Snap",
+      "start": 7
+    },
+    "doc_id": "d0000000000000000000000000000000",
+    "doc_path": "notes/snap.md",
+    "embedding_model": null,
+    "heading_path": [
+      "Snap"
+    ],
+    "index_version": "v1.0",
+    "rank": 1,
+    "retrieval": {
+      "fusion_score": 1.4490997273242101e-6,
+      "lexical_rank": 1,
+      "lexical_score": 1.4490997273242101e-6,
+      "method": "lexical",
+      "vector_rank": null,
+      "vector_score": null
+    },
+    "section_label": "Snap",
+    "snippet": "alpha alpha"
+  },
+  {
+    "chunk_id": "c1000000000000000000000000000000",
+    "chunker_version": "v1",
+    "citation": {
+      "end": 2,
+      "kind": "line",
+      "path": "notes/snap.md",
+      "section": "Snap",
+      "start": 1
+    },
+    "doc_id": "d0000000000000000000000000000000",
+    "doc_path": "notes/snap.md",
+    "embedding_model": null,
+    "heading_path": [
+      "Snap"
+    ],
+    "index_version": "v1.0",
+    "rank": 2,
+    "retrieval": {
+      "fusion_score": 9.641424867368187e-7,
+      "lexical_rank": 2,
+      "lexical_score": 9.641424867368187e-7,
+      "method": "lexical",
+      "vector_rank": null,
+      "vector_score": null
+    },
+    "section_label": "Snap",
+    "snippet": "alpha bravo charlie"
+  }
+]