Generating reports with week numbers ends only at the end of the year

When generating reports with week numbers `timew summary 2025-W43` it generates the report starting from the beginning of the week and until the end of the year. I'd expect it to generate a report for only the week 43 data. I work in 2 week sprints and looking at weekly data is really useful, but currently I have to define the start and end weeks if I use them `timew summary 2025-W43 - 2025-W44`, this is in my opinion contrary to how the day reports work, e.g. `timew summary 2025-10-20` will only generate a report for that day and not starting from that day until the end of the year.

Reproduce the behavior with `timew summary 2025-W43` and compare it with the day-based command `timew summary 2025-10-20`. Trace the week-range handling from the timew CLI entry point, then verify that a week-number query covers only that week while explicit start and end weeks still work.

Written by the indexing model from the issue text.