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/scripts/new-skill.sh

@@ -180,7 +180,8 @@ else
 fi
 echo "" >&2
 echo "Next steps:" >&2
-echo "  1. Fill in $TARGET/SKILL.md — replace all FILL IN: placeholders" >&2
+echo "  1. Fill in $TARGET/SKILL.md — replace all FILL IN: placeholders." >&2
+echo "     Description: 250 chars target / 400 ceiling. Body: 600 / 900, body only." >&2
 echo "  2. Add scripts to scripts/ if needed (or delete the directory)" >&2
 echo "  3. Add docs to references/ if needed (or delete the directory)" >&2
 echo "  4. Add resources to assets/ if needed (or delete the directory)" >&2