docs(bluecraft-agentic-docs): refine documentation structure terminology and patterns

Update skill definition and templates to use "references" instead of "routing"
throughout, clarify the root AGENTS.md as the entry document for agent-docs, and
add explicit linking patterns guidance. Improve template wording to emphasize
directional, explicit references and minimal reference depth.

- Rename and expand linking patterns reference
- Update SKILL.md trigger conditions and core rules
- Refine child doc template compatibility note
- Update refactor checklist to focus on reference depth
- Simplify root AGENTS.md template structure

skills/bluecraft-agentic-docs/references/refactor-checklist.md

@@ -5,7 +5,7 @@ Use this checklist after changing the root `AGENTS.md` or any file in `agent-doc
 - Does each covered document own one clear topic?
 - Does each filename clearly express the document's purpose?
 - Does each opening explain purpose, trigger, and that the document must be followed in scope?
-- Is the `AGENTS.md` at the root of the current Git working tree still the primary routing entrypoint?
+- Is the `AGENTS.md` at the root of the current Git working tree still the root entry document?
 - Does every active `agent-docs/` file have an explicit path from the root?
 - Does each child doc use the right shape for its job: rule doc versus inventory doc?
 - Did you remove stale references, filenames, and replaced paths?
@@ -15,5 +15,5 @@ Use this checklist after changing the root `AGENTS.md` or any file in `agent-doc
 - Is the default path basis still the root of the current Git working tree unless explicitly overridden?
 - Are repository-wide constraints still in the root file?
 - Are topic-specific constraints still in child docs?
-- Did you keep routing depth minimal?
+- Did you keep reference depth minimal?
 - If the repository has a validation command, did you run it?