feat: add governance system for prompt evolution

Implement a comprehensive governance system to manage agent prompt changes safely.

Key features:
- **Proposal Workflow:** Prompt changes are now "proposals" stored in `src/proposals/` with metadata and diffs.
- **Governance Agent:** A new `governance-agent` reviews and applies proposals using `scripts/governance/process-proposals.mjs`.
- **Validation:** Strict validation ensures changes are limited to allowed directories (`src/prompts/daily|weekly`) and preserve required headers.
- **Lock Enhancements:** Lock events now include `promptHash`, `promptPath`, and `gitCommit` for full auditability.
- **Rollback:** New `torch-lock rollback` command restores prompts from local history (`.torch/prompt-history/`) or git.
- **CLI:** Added `proposal` (create, list, show, apply, reject) and `rollback` commands.

This establishes a "Stage -> Evaluate -> Apply" gate for prompt evolution, preventing silent drift and ensuring constitutional stability.

Co-authored-by: PR0M3TH3AN <[email protected]>

src/cmd-rollback.mjs

@@ -0,0 +1,19 @@
+import { rollbackPrompt } from './services/governance/index.js';
+import { ExitError } from './errors.mjs';
+
+export async function cmdRollback(target, strategy) {
+  if (!target) {
+    console.error('Usage: torch-lock rollback --target <path> [--strategy <hash|latest>]');
+    throw new ExitError(1, 'Missing target');
+  }
+
+  const effectiveStrategy = strategy || 'latest';
+
+  try {
+    const result = await rollbackPrompt(target, effectiveStrategy);
+    console.log(JSON.stringify(result, null, 2));
+  } catch (e) {
+    console.error(`Rollback failed: ${e.message}`);
+    throw new ExitError(1, 'Rollback failed');
+  }
+}