refactor(kyberforge): make skill-write and skill-audit self-contained with shared resources

- Move validate.sh ownership to skill-audit/scripts/ — it is the canonical
  structural validator; skill-write now delegates Step 5 to /skill-audit
- Add skill-write/references/scripts.md and deployment-modes.md for progressive
  disclosure of package runner patterns and plugin cache isolation rules
- Fix skill-audit Step 1 cross-skill path reference (was repo-absolute, now
  skill-relative); add manual fallback for sandboxed/Bash-denied contexts
- Scope Step 2 "read every file" to exclude binaries and unreferenced files
- Fix new-skill.sh next-steps output to reference /skill-audit instead of
  the removed validate.sh
- Remove stale Dependencies section from skill-audit README; flip dependency
  arrow — skill-write depends on skill-audit, not vice versa

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

plugins/kyberforge/skills/skill-write/scripts/new-skill.sh

@@ -84,4 +84,4 @@ echo "  1. Fill in $TARGET/SKILL.md — replace all FILL IN: placeholders"
 echo "  2. Add scripts to scripts/ if needed (or delete the directory)"
 echo "  3. Add docs to references/ if needed (or delete the directory)"
 echo "  4. Add resources to assets/ if needed (or delete the directory)"
-echo "  5. Validate: bash $(dirname "${BASH_SOURCE[0]}")/validate.sh $TARGET"
+echo "  5. Validate: run /skill-audit on $TARGET"