feat(skills): install deepeval skill from confident-ai/deepeval

Adds the deepeval eval-loop skill via `npx skills add` with skills-lock.json
for reproducible reinstalls. Symlinked to Claude Code via .claude/skills/.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016z2ZFYHQCex8yZAMVMTZzZ

skills-lock.json

@@ -0,0 +1,11 @@
+{
+  "version": 1,
+  "skills": {
+    "deepeval": {
+      "source": "confident-ai/deepeval",
+      "sourceType": "github",
+      "skillPath": "skills/deepeval/SKILL.md",
+      "computedHash": "1513200bf41565e1bf84146882166bfb772d96887b0733f320eae5aa86443748"
+    }
+  }
+}