Ten-task TDD plan: service.update_entry, three new routes, template
rewrite, CSS, test migration for the removed notes route, end-to-end
isolation test, manual UI verification, and PR opening.
Adds the brainstorm-phase design for inline name/amount/notes edit on
the budget template page. Layout variant A (swap in place), notes folded
into edit mode, no schema change, forward-facing only.
Also adds .superpowers/ to .gitignore so the brainstorm companion's
working dir does not end up tracked.
