v0.3.0: Fix slash commands — add 9 workflows for Antigravity IDE

- Fix workflow frontmatter: remove 'name:' field (Antigravity uses
  filename as command name), add numbered steps format
- Add 6 new workflows: /debug, /tdd, /review, /verify, /finish-branch,
  /worktree — now 9 slash commands total
- Add workflow frontmatter validation to validate command
- Update check-pack.mjs for new workflow files
- Bump version to 0.3.0

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "antigravity-superpowers",
-  "version": "0.2.0",
+  "version": "0.3.0",
   "description": "CLI to initialize the Antigravity Superpowers .agent profile",
   "type": "module",
   "bin": {