Add integration testing guide and prompts

- docs/workflow/INTEGRATION-TESTING.md - Full guide on integration testing
  - What it is vs unit/e2e tests
  - 5 principles to test per integration point
  - Folder structure suggestions
  - Self-improving loop for human findings
- integration-tests/ - Template for project's integration tests
  - README.md - What to test (Feynman fills per project)
  - package.json - Test runner setup
  - scripts/setup.sh - Service startup
  - scripts/teardown.sh - Cleanup
- docs/workflow/WORKFLOW.md - Added integration testing references
- docs/workflow/AGENT-PROMPTS.md - Added integration testing prompts
- docs/workflow/INDEX.md - Updated file structure

integration-tests/package.json

@@ -0,0 +1,15 @@
+{
+  "name": "integration-tests",
+  "version": "1.0.0",
+  "description": "Integration tests for this project",
+  "private": true,
+  "scripts": {
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "test:setup": "bash scripts/setup.sh",
+    "test:teardown": "bash scripts/teardown.sh"
+  },
+  "devDependencies": {
+    "vitest": "latest"
+  }
+}