feat: introduce archify skill for generating architecture diagrams

- Added a new Archify skill, enabling users to create polished architecture, workflow, sequence, data-flow, and lifecycle diagrams.
- Implemented comprehensive functionality including rendering, validation, and delivery of diagrams in various formats.
- Integrated a user-friendly command-line interface for generating and previewing diagrams.
- Developed supporting files including package.json, LICENSE, and SKILL.md for documentation and licensing.
- Added unit tests to ensure reliability and functionality of the new skill.

These changes enhance the application by providing a structured approach to visualizing system architecture and workflows, improving user experience and data representation.

.agents/skills/archify/test/fixtures/fail-migration-cleanup.mjs

@@ -0,0 +1,17 @@
+import fs from 'node:fs';
+import path from 'node:path';
+
+const originalRmSync = fs.rmSync.bind(fs);
+let injectedFailure = false;
+
+fs.rmSync = function failMigrationCleanupOnce(target, options) {
+  const isMigrationStagingDirectory = path.basename(String(target)).startsWith('.archify-migration-');
+  if (!injectedFailure && isMigrationStagingDirectory) {
+    injectedFailure = true;
+    originalRmSync(target, options);
+    const error = new Error('simulated migration cleanup failure');
+    error.code = 'EPERM';
+    throw error;
+  }
+  return originalRmSync(target, options);
+};