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-app/tests/fixtures/workspace/intro.md

@@ -0,0 +1,24 @@
+---
+title: Introduction to Rust
+tags: [rust, language]
+lang: en
+created_at: 2024-03-01T00:00:00Z
+updated_at: 2024-03-02T00:00:00Z
+source_type: note
+trust_level: primary
+---
+
+# Introduction to Rust
+
+Rust is a systems programming language focused on safety, speed, and concurrency.
+The compiler enforces memory safety without a garbage collector.
+
+## Ownership
+
+Each value has a single owner. When the owner goes out of scope the value is
+dropped. References are borrows that the compiler tracks at compile time.
+
+## Concurrency
+
+Threads in Rust use the ownership system to prevent data races. The Send and
+Sync traits codify which types can move between threads.

crates/kebab-app/tests/fixtures/workspace/notes/cargo.md

@@ -0,0 +1,23 @@
+---
+title: Cargo Notes
+tags: [rust, cargo, tools]
+lang: en
+created_at: 2024-04-01T00:00:00Z
+updated_at: 2024-04-02T00:00:00Z
+source_type: note
+trust_level: primary
+---
+
+# Cargo Notes
+
+Cargo is the Rust package manager and build tool.
+
+## Workspaces
+
+A workspace is a set of packages that share the same `Cargo.lock` and output
+directory. Member crates are listed under `[workspace.members]`.
+
+## Features
+
+Cargo features let crates expose optional functionality behind a feature flag.
+Default features are enabled unless `default-features = false` is set.

crates/kebab-app/tests/fixtures/workspace/notes/python.md

@@ -0,0 +1,23 @@
+---
+title: Python Snippets
+tags: [python, language]
+lang: en
+created_at: 2024-05-01T00:00:00Z
+updated_at: 2024-05-02T00:00:00Z
+source_type: note
+trust_level: primary
+---
+
+# Python Snippets
+
+Quick reference for everyday Python tasks.
+
+## List comprehensions
+
+Filter and transform in one pass: `[x*2 for x in xs if x > 0]`. Cleaner than
+the map+filter pair when the predicate is simple.
+
+## Decorators
+
+Wrap a function in another function. `functools.wraps` preserves the
+docstring and `__name__` of the inner function on the outer wrapper.