feat(ai): add ADR-036 unified OCR architecture and frontend test coverage

- Add ADR-036 unified OCR architecture (typhoon-ocr via Ollama)
- Extend AI execution profiles for OCR sandbox configuration
- Add comprehensive frontend test coverage (components, hooks, services)
- Add backend test coverage for document-numbering services
- Update OCR sidecar with typhoon-ocr integration
- Add AI policy service and execution profile management
- Update AGENTS.md and architecture documentation

frontend/lib/i18n/__tests__/index.test.ts

@@ -0,0 +1,36 @@
+// File: frontend/lib/i18n/__tests__/index.test.ts
+// Change Log:
+// - 2026-06-14: Add coverage for Thai/English translators and template replacement
+
+import { describe, expect, it } from 'vitest';
+import { createT, t } from '../index';
+
+describe('i18n utility', () => {
+  it('default translator ควรใช้ภาษาไทย', () => {
+    expect(t('workflow.action.APPROVE')).toBe('อนุมัติ');
+  });
+
+  it('createT ควรสร้าง translator ภาษาอังกฤษได้', () => {
+    const translate = createT('en');
+    expect(translate('workflow.action.APPROVE')).toBe('Approve');
+  });
+
+  it('ควรคืน key เดิมเมื่อไม่พบข้อความ', () => {
+    const translate = createT('th');
+    expect(translate('missing.translation.key')).toBe('missing.translation.key');
+  });
+
+  it('ควรแทนค่า template params ด้วย string หรือ number', () => {
+    const translate = createT('en');
+    expect(translate('ai.staging.thresholdWarningDesc', { rate: 42 })).toBe(
+      'Override rate reached 42% in recent records.'
+    );
+    expect(translate('ai.prompt.resultVersionBadge', { version: '3' })).toBe('Extracted with v3');
+  });
+
+  it('ควรแทนค่า missing template param เป็นค่าว่าง', () => {
+    const translate = createT('en');
+    expect(translate('ai.prompt.resultVersionBadge')).toBe('Extracted with v{{version}}');
+    expect(translate('ai.prompt.resultVersionBadge', {})).toBe('Extracted with v');
+  });
+});