Paint solid token-meter cells as background, not as a block glyph - #1183

The fleet meter fixed hairline row seams by painting full cells as
background (#1183). The project dashboard kept a simplified path that
still used FULL BLOCK glyphs, so the same brick seams showed there.

Move column paint helpers into token_meter and use them for both
meters so solid bars stay solid on every font.

Two fixes to the hover detail.

The cached figure was marked with `↺`, which reads as "refresh" and has
to be learned before the row can be read. It now says the word: `18k ·
9.0k cached`. The box was already sized from its rows, so it just gets
wider.

The bars ended on a partial block glyph, inherited from the column paint.
That cost a square edge: cells a band fills outright are painted as
background, and a foreground block beside them is only drawn where the
font puts ink — a font that draws it short of the line box (#1183)
notches the bar's corner, which reads as damage rather than precision.
Bars now spend whole cells only, every one a background fill, so the
rectangle is clean on any font. Largest-remainder apportionment keeps the
cached and fresh parts summing to exactly the bar's length and keeps a
band with volume from rounding away.

A column still needs its eighths — it is a few cells tall and buys
resolution there, against empty background where the glyph's leading
doesn't show. A twenty-cell bar doesn't need them, so the horizontal axis
machinery added for it is gone again; what remains of the sharing is
`split_units`, the largest-remainder split both resolutions use.

* Detail a hovered token-meter column as bars per model

Hovering a meter column listed its models as one line of comma-separated
figures. A column is a stack, and the questions asked of it — what was
this mostly, how much of it was real work — are about proportion, so the
division was left to be done by eye; past two models the line read as a
run of text with no shape at all.

The detail is now a small panel: the span and the column's total, then
one row per model with its name, a horizontal bar of that model's share,
and its exact figures (cache-served volume marked as the subset it is).
The bars are the column's own paint laid along a row instead of up one —
one hue per model, the cache-served part in the darker tone at the bar's
start, boundaries carried at eighth resolution — so the detail describes
the graph under the pointer rather than a second vocabulary for it.

Rows follow series order, the order the column stacks them and the
legend names them, so a row's position matches its band. Bars scale to
the hovered column's total, and a model that did any work keeps a
visible bar however small its share. A terminal too narrow for a bar
that would still separate a tenth from a fifth falls back to the
previous text detail rather than drawing a stub bar.

The project dashboard's meter had no hover detail at all; it now records
its graph rect and shares this one renderer, since scoping the meter to
a project changes which sessions are counted, not what the graph means.

Column paint gains a horizontal axis (`bar_cells`) rather than a second
implementation: same eighth arithmetic and the same fg-over-bg encoding
for a boundary inside a cell, only the glyph table differs.

* Spell out "cached", and keep the hover bars square

Two fixes to the hover detail.

The cached figure was marked with `↺`, which reads as "refresh" and has
to be learned before the row can be read. It now says the word: `18k ·
9.0k cached`. The box was already sized from its rows, so it just gets
wider.

The bars ended on a partial block glyph, inherited from the column paint.
That cost a square edge: cells a band fills outright are painted as
background, and a foreground block beside them is only drawn where the
font puts ink — a font that draws it short of the line box (#1183)
notches the bar's corner, which reads as damage rather than precision.
Bars now spend whole cells only, every one a background fill, so the
rectangle is clean on any font. Largest-remainder apportionment keeps the
cached and fresh parts summing to exactly the bar's length and keeps a
band with volume from rounding away.

A column still needs its eighths — it is a few cells tall and buys
resolution there, against empty background where the glyph's leading
doesn't show. A twenty-cell bar doesn't need them, so the horizontal axis
machinery added for it is gone again; what remains of the sharing is
`split_units`, the largest-remainder split both resolutions use.