feat(governance): add prompt versioning, rollback --list, and state backup

- governance/index.js: archive filenames now include ISO timestamp for
  deterministic sorting (<base>_<ts>_<hash>.md); write .meta.json sidecar
  on every archive with proposalId, author, reason, and archivedAt
- governance/index.js: add listPromptVersions(target) — returns archived
  versions for a prompt sorted newest-first with sidecar metadata surfaced
- cmd-rollback.mjs: add --list flag to list available versions without
  restoring (delegates to listPromptVersions)
- cli-parser.mjs: add --list and --output flags
- lib.mjs: pass list flag to cmdRollback; add backup command dispatch
- cmd-backup.mjs: new torch-lock backup command — snapshots
  .scheduler-memory/memory-store.json and scheduler run state to
  .torch/backups/<timestamp>/; supports --output override and --list
- docs/prompt-versioning.md: comprehensive guide to the full
  proposal → apply → list-versions → rollback workflow, state backup
  and restore procedure, and storage location reference
- test/governance.test.mjs: 7 scenario-based tests (SCN-proposal-create,
  SCN-proposal-list, SCN-proposal-reject, SCN-archive-naming,
  SCN-version-list, SCN-rollback-latest, SCN-rollback-hash)

https://claude.ai/code/session_01Ndq2D72Kp77BYo4owD63uY

src/lib.mjs

@@ -723,7 +723,18 @@ export async function main(argv) {
       }
 
       case 'rollback': {
-        await cmdRollback(args.target, args.strategy);
+        await cmdRollback(args.target, args.strategy, { list: args.list });
+        break;
+      }
+
+      case 'backup': {
+        const { cmdBackup, listBackups } = await import('./cmd-backup.mjs');
+        if (args.list) {
+          const backups = await listBackups();
+          console.log(JSON.stringify(backups, null, 2));
+        } else {
+          await cmdBackup({ output: args.output });
+        }
         break;
       }