Add comprehensive documentation for employee learning platform

- Created handover document outlining design decisions and application functionality.
- Developed implementation plan detailing phased approach for service development.
- Specified ingestion service responsibilities, API surface, and processing pipeline.

PROTECTED.md

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+# Protected files — do not modify
+
+These files and directories must never be modified by Claude Code.
+They belong to the existing deployment pipeline and are frozen.
+
+## Pipeline and CI/CD
+.github/
+.github/workflows/
+.gitlab-ci.yml (if present)
+
+## Container and orchestration
+Dockerfile
+docker-compose.yml
+docker-compose.prod.yml
+docker-compose.override.yml (if present)
+
+## Infrastructure and provisioning
+ansible/
+nginx/
+
+## Stylesheet
+stylesheet.css (repo root — use as-is, do not modify)
+
+## Environment templates at repo root
+.env.example (repo root only — services may have their own)
+
+## Legacy prototype
+legacy/
+
+---
+
+The only infrastructure file that will change is Dockerfile, and only in
+Phase 8 step 8.5. That change is made manually by the human, not by
+Claude Code.