test: add unit tests for core modules (#35)

Cover high-priority untested modules:
- util: base32, result, refs-field, storage-root, log-tag
- util-agent: storage (normalizeWorkflowConfig, resolveStorageRoot), run (parseArgv)
- agent-builtin: tools (read-file, write-file, run-command), session, detail

627 → 719 tests (+92), all passing.

Refs #35

packages/util/__tests__/storage-root.test.ts

@@ -0,0 +1,25 @@
+import { describe, it, expect } from 'vitest';
+import { homedir } from 'node:os';
+import { getDefaultStorageRoot, getDefaultWorkflowStorageRoot, getGlobalCasDir } from '../src/storage-root.js';
+
+describe('getDefaultStorageRoot', () => {
+  it('returns homedir + /.uwf', () => {
+    expect(getDefaultStorageRoot()).toBe(homedir() + '/.uwf');
+  });
+});
+
+describe('getDefaultWorkflowStorageRoot', () => {
+  it('returns same as getDefaultStorageRoot (deprecated alias)', () => {
+    expect(getDefaultWorkflowStorageRoot()).toBe(getDefaultStorageRoot());
+  });
+});
+
+describe('getGlobalCasDir', () => {
+  it('appends /cas to given storage root', () => {
+    expect(getGlobalCasDir('/tmp/test')).toBe('/tmp/test/cas');
+  });
+
+  it('falls back to default when undefined', () => {
+    expect(getGlobalCasDir(undefined)).toBe(homedir() + '/.uwf/cas');
+  });
+});