feat: install korean technical blog skill bundle

.agents/skills의 technical-document-author,
revising-korean-technical-prose, writing-natural-korean을
korean-technical-blog-skills-bundle-v1의 세 스킬로 교체한다.

- writing-korean-technical-blogs: 문제·제약·선택·구현·결과·한계 구조화
- reducing-ai-like-korean-writing: 상투성·추상화·반복 제거
- editing-korean-grammar-and-expression: 맞춤법·띄어쓰기·호응 검수

상류를 수정하지 않고 복사했다. diff -r 0건, MANIFEST.sha256 검증 통과,
번들 validate_skill.py 3/3 PASS.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.agents/skills/writing-korean-technical-blogs/profiles/performance-case-study.yaml

@@ -0,0 +1,18 @@
+id: performance-case-study
+register: preserve_or_hamnida
+use_when: 응답 시간, 처리량, 오류율, 자원 사용량 등 전후 성능을 설명할 때
+required_sections:
+  - baseline_and_problem
+  - metric_definition
+  - environment_and_conditions
+  - hypotheses_and_changes
+  - before_after_results
+  - regressions_and_limitations
+optional_sections:
+  - failed_attempts
+  - dashboards
+  - code_or_query
+rules:
+  put_key_result_in_first_15_percent: true
+  never_report_metric_without_scope: true
+  keep_adverse_results: true