refactor: Reorganize docs into subfolders and add testing strategy

- docs/architecture/ - ARCHITECTURE.md, ARCHITECTURAL_GUARDRAILS.md
- docs/planning/ - LAUNCH_PLAN.md, PROJECT_SUMMARY.md, BUILD_SUMMARY.md
- docs/policy/ - PRIVACY_POLICY, SECURITY, CODE_OF_CONDUCT, etc.
- docs/testing/ - cardsnap_e2e_test_plan.md, TESTING_STRATEGY.md (new)
- Add TESTING_STRATEGY.md documenting current tests vs best practices

AI-Generated: Yes
Model: Claude (Sisyphus)
Platform: OpenCode

Author: rprabhat

.gitignore

@@ -88,6 +88,10 @@ Gemfile.lock
 docs/
 !docs/index.html
 !docs/images/
+!docs/architecture/
+!docs/planning/
+!docs/policy/
+!docs/testing/
 fastlane/
 scripts/
 setup-and-verify.sh