Execute plan loop

Load and follow these conventions during the whole loop: git-commit-organizer, no-slop-code, decision-record-log, scratchpad-working-files, simplified-technical-language.

Before the first step

1. Read the plan and the spec. Read .scratchpad/<slug>/progress.md if it exists and continue from the first step that is not done.
2. Run the full test suite and record the baseline (number of tests, all passing).
3. Prepare the smallest way to run the change by hand, isolated from real data (for example a server on its own port with a scratch database, or a CLI call on a scratch folder). Put its start and stop commands in .scratchpad/<slug>/manual-env.sh. Check that its ports are free first. Another project can hold them. Never stop a process that you did not start.

For each step

1. Implement the minimum that the step describes. Nothing from later steps.
2. Test. Add or update tests for the criteria of the step. For fixes, check that the new test fails without the fix, then passes with it.
3. Run the full check of the project (for example types, lint and all tests).
4. Manual check. Do the check that the plan lists, in the manual environment. Stop everything you started.
5. Record and commit. Write the ADRs that decision-record-log asks for (if the project switched it off, the reason goes in the commit body), sync the docs the change affects, and commit as git-commit-organizer says.
6. Update progress.md with the status and the commit hashes. Do not start the next step before progress.md shows the commit of this one.