chore: workspace-wide cleanup — clippy::pedantic baseline + auto-fix

cut PR v0.18.0 전 마지막 정리. 사용자 요청: "전체 코드베이스를 깔끔하고 알아보기 쉽게".

## Workspace lints

- `Cargo.toml` 의 `[workspace.lints.clippy]` 에 `pedantic = "warn"` (priority -1) + 의도적 allow-list 추가:
  - cast_possible_truncation / cast_possible_wrap / cast_sign_loss / cast_precision_loss — ONNX i64 / hash modular reduction 등 의도적 truncation.
  - doc_markdown / missing_errors_doc / missing_panics_doc — cosmetic doc style.
  - too_many_lines / module_name_repetitions / must_use_candidate / needless_pass_by_value / manual_let_else / items_after_statements / similar_names — informational only.
  - format_collect / match_wildcard_for_single_variants / trivially_copy_pass_by_ref / unnecessary_wraps — intentional patterns (exhaustive match, future Result variants 등).
  - default_trait_access — `Foo::default()` 가 idiomatic.
  - float_cmp — NLI / RRF score 의 explicit threshold 비교 의도.
  - struct_excessive_bools / case_sensitive_file_extension_comparisons / naive_bytecount / ignore_without_reason — domain-specific 의도.
  - format_push_string / return_self_not_must_use / match_same_arms — builder / wire-label / hot-path 패턴 보존.
  - needless_continue / used_underscore_binding / nonminimal_bool / unreadable_literal / many_single_char_names / doc_link_with_quotes / assigning_clones / collapsible_str_replace / trivial_regex / elidable_lifetime_names / range_plus_one / explicit_iter_loop / implicit_hasher / ref_option — remaining low-value style.
- 각 24 crate `Cargo.toml` 에 `[lints] workspace = true` 추가.

## Auto-fix

`cargo clippy --workspace --all-targets --fix` 적용 — 128 files changed, 552 insertions / 472 deletions. 주로:
- uninlined_format_args (~18): `format!("{}", x)` → `format!("{x}")`.
- redundant_closure_for_method_calls (~33): `.map(|x| x.foo())` → `.map(T::foo)`.
- 그 외 mechanical refactor.

## 검증

- `cargo clippy --workspace --all-targets -j 1 -- -D warnings` clean (pedantic + 모든 lint group).
- `cargo test --workspace --no-fail-fast -j 1` — **1293 tests pass + 1 pre-existing flaky fail** (`kebab-mcp::tools_call_ask_multi_hop::ask_tool_routes_multi_hop_true_to_decompose_first`, HOTFIX candidate, cleanup 무관). 회귀 0.

Wire 영향: 없음.
Behavior 영향: 없음 (mechanical refactor only).

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

crates/kebab-config/Cargo.toml

@@ -22,3 +22,6 @@ tracing      = { workspace = true }
 
 [dev-dependencies]
 tempfile     = { workspace = true }
+
+[lints]
+workspace = true

crates/kebab-config/src/paths.rs

@@ -157,7 +157,7 @@ mod tests {
 
     #[test]
     fn xdg_data_home_set_replaces_var() {
-        let _lock = ENV_LOCK.lock().unwrap_or_else(|p| p.into_inner());
+        let _lock = ENV_LOCK.lock().unwrap_or_else(std::sync::PoisonError::into_inner);
         let _guard = XdgGuard::capture();
         // SAFETY: lock held for the duration of this test.
         unsafe { std::env::set_var("XDG_DATA_HOME", "/custom/path") };
@@ -168,7 +168,7 @@ mod tests {
 
     #[test]
     fn xdg_data_home_unset_uses_default() {
-        let _lock = ENV_LOCK.lock().unwrap_or_else(|p| p.into_inner());
+        let _lock = ENV_LOCK.lock().unwrap_or_else(std::sync::PoisonError::into_inner);
         let _guard = XdgGuard::capture();
         // SAFETY: lock held for the duration of this test.
         unsafe { std::env::remove_var("XDG_DATA_HOME") };
@@ -181,7 +181,7 @@ mod tests {
 
     #[test]
     fn xdg_with_no_default_resolves_to_empty_when_unset() {
-        let _lock = ENV_LOCK.lock().unwrap_or_else(|p| p.into_inner());
+        let _lock = ENV_LOCK.lock().unwrap_or_else(std::sync::PoisonError::into_inner);
         let _guard = XdgGuard::capture();
         // SAFETY: lock held for the duration of this test.
         unsafe { std::env::remove_var("XDG_DATA_HOME") };
@@ -193,7 +193,7 @@ mod tests {
 
     #[test]
     fn leading_tilde_expands_to_home() {
-        let _lock = ENV_LOCK.lock().unwrap_or_else(|p| p.into_inner());
+        let _lock = ENV_LOCK.lock().unwrap_or_else(std::sync::PoisonError::into_inner);
         let home = std::env::var("HOME").expect("HOME must be set in tests");
         let p = expand_path("~/runs", "");
         assert_eq!(p, PathBuf::from(home).join("runs"));
@@ -229,7 +229,7 @@ mod tests {
 
     #[test]
     fn tilde_path_ignores_base_dir() {
-        let _lock = ENV_LOCK.lock().unwrap_or_else(|p| p.into_inner());
+        let _lock = ENV_LOCK.lock().unwrap_or_else(std::sync::PoisonError::into_inner);
         let home = std::env::var("HOME").expect("HOME must be set in tests");
         let base = Path::new("/tmp/ignored-cfg");
         let p = expand_path_with_base("~/x", "", base);
@@ -238,7 +238,7 @@ mod tests {
 
     #[test]
     fn xdg_var_path_ignores_base_dir() {
-        let _lock = ENV_LOCK.lock().unwrap_or_else(|p| p.into_inner());
+        let _lock = ENV_LOCK.lock().unwrap_or_else(std::sync::PoisonError::into_inner);
         let _guard = XdgGuard::capture();
         // SAFETY: lock held for the duration of this test.
         unsafe { std::env::set_var("XDG_DATA_HOME", "/xdg/data") };
@@ -255,7 +255,7 @@ mod tests {
         // Order matters: substitute `{data_dir}` (which itself contains
         // an unexpanded `${XDG_DATA_HOME}` and `~`), then the other two
         // resolve the result.
-        let _lock = ENV_LOCK.lock().unwrap_or_else(|p| p.into_inner());
+        let _lock = ENV_LOCK.lock().unwrap_or_else(std::sync::PoisonError::into_inner);
         let _guard = XdgGuard::capture();
         // SAFETY: lock held for the duration of this test.
         unsafe { std::env::set_var("XDG_DATA_HOME", "/xdg/data") };