docs(bluecraft-agentic-docs): document explicit linking patterns and update skill rules

Add dedicated reference for root AGENTS.md to agent-docs linking patterns with
anti-patterns and explicit reference requirements. Update SKILL.md core rules to
emphasize directional, explicit references and minimal reference depth. Refine
template structures in inventory-doc-template.md and root-agents-template.md to
enforce clearer scope sections and required reading lists. Update agent interface
metadata to reflect focused maintenance scope.

skills/bluecraft-agentic-docs/references/inventory-doc-template.md

@@ -9,11 +9,11 @@ Use this structure for Markdown files inside `agent-docs/` when the document's m
 
 <Opening statement: what this inventory tracks, when it should be used or updated, and that it must be followed in scope.>
 
-## Use This For
+## Applies To
 
 - <tasks that require reading or updating this inventory>
 
-## Do Not Use This For
+## Does Not Apply To
 
 - <tasks that belong in a rule doc, public docs, or another inventory>