fix(config): satisfy clippy::bool_assert_comparison in pdf_ocr tests

fd918a6 의 F2 test file (crates/kebab-config/tests/pdf_ocr.rs) 의 4 line
`assert_eq!(bool_field, true|false)` 가 workspace clippy pedantic
의 `bool_assert_comparison` 위반 → CI gate
`cargo clippy --workspace --all-targets -- -D warnings` exit 1.

각 assertion 의 canonical form 적용:
- assert_eq!(x, false) → assert!(!x)
- assert_eq!(x, true)  → assert!(x)

semantic + behavior 동일, 4 line edit, logic 변경 0.

review trail:
- impl result: .omc/reviews/2026-05-27-pdf-ocr-step-05-impl-result.md
- spec review: .omc/reviews/2026-05-27-pdf-ocr-step-05-spec-review-result.md (I-1)

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

crates/kebab-config/tests/pdf_ocr.rs

@@ -45,8 +45,8 @@ lang_hint = "kor"
 #[test]
 fn pdf_ocr_defaults_off_with_qwen_3b() {
     let cfg = Config::defaults();
-    assert_eq!(cfg.pdf.ocr.enabled, false);
-    assert_eq!(cfg.pdf.ocr.always_on, false);
+    assert!(!cfg.pdf.ocr.enabled);
+    assert!(!cfg.pdf.ocr.always_on);
     assert_eq!(cfg.pdf.ocr.engine, "ollama-vision");
     assert_eq!(cfg.pdf.ocr.model, "qwen2.5vl:3b");
     assert!(cfg.pdf.ocr.endpoint.is_none());
@@ -69,9 +69,9 @@ fn pdf_ocr_env_overrides() {
 
     let cfg = Config::defaults().apply_env(&env);
 
-    assert_eq!(cfg.pdf.ocr.enabled, true);
+    assert!(cfg.pdf.ocr.enabled);
     assert_eq!(cfg.pdf.ocr.model, "qwen2.5vl:7b");
-    assert_eq!(cfg.pdf.ocr.always_on, true);
+    assert!(cfg.pdf.ocr.always_on);
     assert!((cfg.pdf.ocr.valid_ratio_threshold - 0.75).abs() < 1e-6);
 
     // 다른 env var 가 default 보존