Weekly (7d) usage bar shows 10 segments instead of 7

[Lexx-Agency-dev]

Currently both the 5h and 7d usage bars use the same fixed segment count
(SEGMENT_COUNT = 10 in src/window.rs, used via row_bar_segment_count
when only one model is active).

For the 7-day window, 10 segments don't map cleanly onto 7 days, which
makes the bar a bit confusing to read at a glance (each segment doesn't
correspond to a meaningful unit of time).

Suggestion:
Change the segment count for the 7d bar to 7, so each segment represents
one day. Optionally, the 5h bar could also use 7 segments for visual
consistency between the two rows.

I tested this locally by changing:

const SEGMENT_COUNT: i32 = 10;

to:

const SEGMENT_COUNT: i32 = 7;

in src/window.rs. Since this constant is only used for the
active_models == 1 case, it doesn't affect the 2/3-model layouts
(which already use 5 and 4 segments respectively).

Would you be open to this change, either as the new default or as a
configurable option in the right-click menu (similar to language /
update frequency settings)? Happy to open a PR if you'd like a specific
approach.