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-mcp/tests/tools_call_search.rs

@@ -71,8 +71,7 @@ async fn search_tool_returns_search_response_v1() {
 
     assert!(
         !result.is_error.unwrap_or(false),
-        "expected isError=false, got {:?}",
-        result
+        "expected isError=false, got {result:?}"
     );
 
     let content = result
@@ -108,7 +107,7 @@ async fn search_tool_returns_search_response_v1() {
     );
     // truncated must be present (bool); next_cursor may be null on last page.
     assert!(
-        v.get("truncated").and_then(|t| t.as_bool()).is_some(),
+        v.get("truncated").and_then(serde_json::Value::as_bool).is_some(),
         "envelope should carry truncated:bool"
     );
     assert!(
@@ -172,8 +171,7 @@ async fn search_with_doc_id_filter_returns_only_target() {
     );
     assert!(
         !unfiltered.is_error.unwrap_or(false),
-        "unfiltered search failed: {:?}",
-        unfiltered
+        "unfiltered search failed: {unfiltered:?}"
     );
     let unfiltered_text = match &unfiltered.content.first().unwrap().raw {
         RawContent::Text(t) => t.text.clone(),
@@ -211,8 +209,7 @@ async fn search_with_doc_id_filter_returns_only_target() {
     );
     assert!(
         !filtered.is_error.unwrap_or(false),
-        "filtered search failed: {:?}",
-        filtered
+        "filtered search failed: {filtered:?}"
     );
     let filtered_text = match &filtered.content.first().unwrap().raw {
         RawContent::Text(t) => t.text.clone(),