feat(kyberforge): enforce the ADR-0020 context contract for skills and agents

Skill name+description pairs are preloaded into every session, costing
~6,200 tokens across 39 skills before any skill is invoked. The authoring
rules mandated that growth: skill-author:104 and description-quality.md:21
both required padding, while skill-author:102 (the deflating rule) had no
FAIL condition behind it.

Gates (blocking, no baseline file):
- description 250 chars SUGGESTION / 400 FAIL, measured on the folded
  YAML value
- body-only 600 words SUGGESTION / 900 FAIL, independent of the unchanged
  whole-file 2770-word / 500-line spec backstop
- every boundary-clause routing target must resolve to a real skill or
  agent; catches skill-improve, neuledge-context and gitea-labels
- agents take the description gates but deliberately no body gate; a test
  pins that absence

Vale: DescriptionOpener widened to ^This\b, new CompositionNote rule
banning architecture notes from descriptions. 10 hits, 0 false positives.

Kyberforge's own four skills retrofitted: descriptions 3,364 -> 938 chars
(-72%), bodies 8,306 -> 2,487 words (-70%), all via the apm-workflow
dispatch pattern. Fixes the skill-improve dangling route and the
agent-author misroute to manual review.

Also fixes a pre-existing false positive where any line-initial 'read '
was flagged as interactive input, which had already caused two scripts to
be rewritten around it.

Refs: ADR-0020

plugins/kyberforge/skills/skill-author/assets/templates/references/README.md

@@ -5,9 +5,17 @@ without bloating its core context.
 
 ## When to add a reference file
 
-Move content here when SKILL.md is approaching 500 lines, or when a topic
-is only relevant in specific circumstances (error handling, edge cases,
-domain-specific sub-procedures).
+The SKILL.md body carries the decision procedure only. Everything else lives
+here: lookup tables, spec restatements, output schemas, templates, example
+blocks, rationale prose, and anything only one branch reaches.
+
+Two triggers make a reference file mandatory rather than optional:
+
+- The body is over its 600-word target (900 is a hard failure), counting the
+  body only — everything after the frontmatter's closing `---`.
+- The skill has two or more mutually exclusive flows. The body then keeps only
+  a dispatch table plus the gates common to every branch, and each flow gets
+  its own self-contained file here (e.g. `create.md`, `improve.md`).
 
 ## How to reference from SKILL.md