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-parse-code/src/c.rs

@@ -310,7 +310,7 @@ fn build_blocks(
     // If there is only glue (no real unit) the single pushed "<top-level>"
     // label should be "<module>" — rename it now.
     if !has_real_unit {
-        for (sym, _, _, _) in units.iter_mut() {
+        for (sym, _, _, _) in &mut units {
             if sym == "<top-level>" {
                 *sym = "<module>".to_string();
             }
@@ -329,7 +329,7 @@ fn build_blocks(
             lang: Some("c".to_string()),
         };
         let block_id = id_for_block(doc_id, "code", &[], ordinal as u32, &span);
-        let code = lines[(line_start as usize - 1)..=(line_end as usize - 1)].join("\n");
+        let code = lines[(line_start as usize - 1)..(line_end as usize)].join("\n");
         blocks.push(Block::Code(CodeBlock {
             common: CommonBlock {
                 block_id,
@@ -704,11 +704,11 @@ void print_result(int v) {
 
     #[test]
     fn c_extractor_deterministic_across_runs() {
-        let src = r#"
+        let src = r"
 struct Node { int val; };
 int sum(int a, int b) { return a + b; }
 void noop(void) {}
-"#;
+";
         let a = tests_support::extract_c(src, "x/det.c");
         for _ in 0..20 {
             assert_eq!(