Add project documentation and framework setup

- Initialize project documentation structure
- Add business case and stakeholder analysis
- Create project plan with four milestones
- Setup framework integration via git submodule
- Configure gitignore for project structure

docs/milestones/mil-004-documentation-and-release.md

@@ -0,0 +1,68 @@
+# MIL-004 Documentation and release
+
+## Metadata
+| Key | Value |
+| --- | --- |
+| ID | MIL-004 |
+| CrossReference | [PP-001], [SA-001], [BC-001] |
+
+## Version History
+| Date | Status | Author | Reviewer | Change | Commit |
+| --- | --- | --- | --- | --- | --- |
+| 2026-10-04 | Accepted | Jens Tirsvad Nielsen | S01 | Initial version | pending |
+
+---
+
+## Purpose
+
+Decide whether the project can be handed over: a new user can set it up, run it and test it from the README alone.
+
+## Deliverable
+
+`README.md` following the project template, Doxygen output building without warnings, AGPL licence referenced.
+
+## Go / No-Go Criteria
+
+| # | Criterion (objectively checkable) | Go | No-Go |
+| --- | --- | --- | --- |
+| 1 | README has Overview, Requirements, Setup, Run, Tests, License and Links | Met | Not met |
+| 2 | README explains creating `.venv` and `python -m pip install --upgrade pip` | Met | Not met |
+| 3 | `doxygen Doxyfile` builds with no warnings | Met | Not met |
+| 4 | Following the README on a clean clone, the program runs and the tests pass | Met | Not met |
+
+## Dependencies
+
+| Depends on | Reason |
+| --- | --- |
+| MIL-003 | Documents the finished program |
+
+## Traceability
+
+| Business Case objective / KPI / user story | Reference |
+| --- | --- |
+| Objectives 1 to 4 | [BC-001] |
+
+## Ownership
+
+| Role | Stakeholder ID (SA) |
+| --- | --- |
+| Owner | S01 |
+| Approving reviewer | S01 |
+
+## Target Date
+
+2026-10-08
+
+## Tasks
+
+| # | Task | Summary | Needs its own Use Case/User Story? | Reference |
+| --- | --- | --- | --- | --- |
+| 1 | Write README.md | README from the project template with calculator-specific text: venv setup, pip upgrade, run, tests, AGPL license and links. | No |  |
+| 2 | Verify Doxygen build | Run `doxygen Doxyfile` and fix any warnings so every module and function is documented. | No |  |
+| 3 | Verify setup from a clean clone | Follow the README in a fresh `.venv` to confirm install, run and test commands work as written. | No |  |
+
+---
+
+[PP-001]: ../project-plan.md
+[SA-001]: ../stakeholder-analysis.md
+[BC-001]: ../business-case.md