feat(beads): add Release function and gt release command

Implement step recovery mechanism for stuck molecule steps (MVP):
- Add Release() and ReleaseWithReason() to beads wrapper
- Create gt release command to move in_progress → open
- Clears assignee so step can be claimed by another worker
- Optionally adds reason as note for tracking

Usage:
  gt release <id>           # Release single issue
  gt release <id> -r "why"  # Release with reason

This enables nondeterministic idempotence - stuck steps can be
safely recovered and retried by releasing and reclaiming.

Closes gt-g44u.4

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/beads/beads.go

@@ -321,6 +321,27 @@ func (b *Beads) CloseWithReason(reason string, ids ...string) error {
 	return err
 }
 
+// Release moves an in_progress issue back to open status.
+// This is used to recover stuck steps when a worker dies mid-task.
+// It clears the assignee so the step can be claimed by another worker.
+func (b *Beads) Release(id string) error {
+	return b.ReleaseWithReason(id, "")
+}
+
+// ReleaseWithReason moves an in_progress issue back to open status with a reason.
+// The reason is added as a note to the issue for tracking purposes.
+func (b *Beads) ReleaseWithReason(id, reason string) error {
+	args := []string{"update", id, "--status=open", "--assignee="}
+
+	// Add reason as a note if provided
+	if reason != "" {
+		args = append(args, "--notes=Released: "+reason)
+	}
+
+	_, err := b.run(args...)
+	return err
+}
+
 // AddDependency adds a dependency: issue depends on dependsOn.
 func (b *Beads) AddDependency(issue, dependsOn string) error {
 	_, err := b.run("dep", "add", issue, dependsOn)