chore: quantlab-agent 프로젝트 초기 설정

agent_guide 템플릿 기반으로 프로젝트 구조 설정.
Gitea(quantlab-agent), Vikunja(project #15) 연동 완료.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.agent/skills/gsd-cleanup/SKILL.md

@@ -0,0 +1,19 @@
+---
+name: gsd-cleanup
+description: Archive accumulated phase directories from completed milestones
+---
+
+<objective>
+Archive phase directories from completed milestones into `.planning/milestones/v{X.Y}-phases/`.
+
+Use when `.planning/phases/` has accumulated directories from past milestones.
+</objective>
+
+<execution_context>
+@.agent/get-shit-done/workflows/cleanup.md
+</execution_context>
+
+<process>
+Follow the cleanup workflow at @.agent/get-shit-done/workflows/cleanup.md.
+Identify completed milestones, show a dry-run summary, and archive on confirmation.
+</process>