fix(kyberforge): apply cross-skill audit findings to skill factory trio

- validate.sh: move FAIL lines and failure summary to stdout; stderr
  reserved for fatal script errors only (missing SKILL.md, bad args)
- skill-audit SKILL.md: replace concrete plugins/kyberforge/skills/...
  example with abstract placeholder to fix meta-circularity
- skill-write SKILL.md: rephrase placeholder section-heading instruction
  to remove embedded FILL IN: from a code span, clearing validator false positive
- skill-improve SKILL.md: wrap Step 2 root-cause example in a text fence
- skill-write assets/templates/README.md: update Files table to individual-
  file rows so skill-audit can verify per-file coverage

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plugins/kyberforge/skills/skill-write/SKILL.md

@@ -69,7 +69,7 @@ Open `<destination-dir>/<skill-name>/SKILL.md`. Replace every `FILL IN:` placeho
 
 ### Body — include only what the agent lacks
 
-Rename `## FILL IN: <section-name>` to a heading that fits the skill's structure (e.g. `## Step 1`, `## Workflow`, `## Instructions`).
+Rename the placeholder section heading to one that fits the skill's structure — `## Step 1`, `## Workflow`, `## Instructions`, etc.
 
 Ask of every sentence: "Would the agent get this wrong without it?" Cut anything that answers "no."