Symlink whole skills/ dir into vendor configs

The per-skill links meant every new skill needed a matching symlink
added under both .claude/skills/ and .agents/skills/, and forgetting
one silently dropped the skill for that tool. Linking the whole
skills/ directory into each removes that step and that failure mode.

Author: jeffhorn-nava

.agents/skills

@@ -0,0 +1 @@
+../skills

.agents/skills/create-issue

@@ -0,0 +1 @@
+../skills