docs(skill-author): route hook token guidance to primitive-author

deployment-modes.md told authors to use ${CLAUDE_PLUGIN_ROOT} in hook
commands. Hook authoring now belongs to primitive-author, which
specifies the target-neutral ${PLUGIN_ROOT}; point there instead.

Refs #94

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KkT7RSDwDbmrM9T34b6sTi

plugins/kyberforge/.apm/skills/skill-author/SKILL.md

@@ -6,7 +6,7 @@ description: >
   Not read-only review -> `factory-audit`. Not agent files -> `agent-author`.
 allowed-tools: Bash Read Write Edit
 metadata:
-  version: "1.0.5"
+  version: "1.0.6"
   category: factory
   source_keys:
     - agentskills-home