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>

scripts/check-pack.mjs

@@ -30,6 +30,12 @@ const required = [
   "templates/.agent/workflows/brainstorm.md",
   "templates/.agent/workflows/write-plan.md",
   "templates/.agent/workflows/execute-plan.md",
+  "templates/.agent/workflows/debug.md",
+  "templates/.agent/workflows/tdd.md",
+  "templates/.agent/workflows/review.md",
+  "templates/.agent/workflows/verify.md",
+  "templates/.agent/workflows/finish-branch.md",
+  "templates/.agent/workflows/worktree.md",
   "templates/.agent/agents/code-reviewer.md",
   "templates/.agent/tests/run-tests.sh",
   "templates/.agent/tests/check-antigravity-profile.sh",