Fix energy distribution home ring overflowing to 100% grid (#54191)

* Fix energy distribution home ring overflowing to 100% grid

Size the home circle from allocated used_solar, used_battery, and
used_grid instead of net used_total so misaligned hours cannot produce
a negative grid arc.

* Add gallery demo for energy distribution home ring

Mock the issue 54185 daily totals with realistic hourly PV, battery,
and grid statistics, including an export-lagged card that overflows
the old ring math.

* Remove gallery energy distribution demo from this PR

Keep the home-ring fix and its unit tests; drop the gallery page
that was only used for local browser verification.

* Keep a zero-consumption home ring as a plain border

When solar is configured but allocated flows are all zero, leave the
arcs unset so the card can show the home outline instead of zero-length
dashes on a borderless circle.

* Keep a defined zero low-carbon home arc

The energy distribution card mounts the home SVG when solar or
lowCarbon is defined. Omitting a 0 leftover hid grid and battery
arcs on a no-solar 100% high-carbon ring.