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-audit/scripts/validate.sh

@@ -50,7 +50,7 @@ def ok(msg):
 
 def fail(msg):
     global failed
-    print(f"FAIL  {msg}", file=sys.stderr)
+    print(f"FAIL  {msg}")
     failed = True
 
 # --- Parse frontmatter ---
@@ -174,6 +174,6 @@ if not failed:
     print("All checks passed.")
     sys.exit(0)
 else:
-    print("One or more checks failed.", file=sys.stderr)
+    print("One or more checks failed.")
     sys.exit(1)
 PYTHON