fix(#4294): reserve a full progress bar for 100% and give the render half one owner (#4473)

* fix(#4294): reserve a full progress bar for 100% and give the render half one owner

Six call sites each carried `Math.round((percent / 100) * width)` inline, and
every copy rounded to a full bar before the percent reached 100: from 95 up at
width 10, from 98 up at width 20. A project at 19/20 plans drew the same bar as
a shipped one beside a number that said otherwise, and an out-of-range percent
threw `RangeError` from the unguarded `'░'.repeat`.

ADR-3180 Decision 7 gave the completion-RATIO derivation one owner
(`clampPercentFromFraction`). This gives the RENDER half the same:
`progressBarFilledCells` / `renderProgressBar` in phase-lifecycle.cts, with the
`progress` table and bar renderers, the stats renderer, the gsd2 import writer,
and #4231's `formatProgressMachineSegment` (which now serves both STATE.md
writers) all drawing through it.

Contract: below 100 the fill is held one cell short of the width, so only the
saturating percents move (95-99 at width 10, 98-99 at width 20) and every other
value in 0-100 renders as before — pinned by an exhaustive comparison against
the legacy formula at both widths. Null / non-finite renders an empty bar;
out-of-range is clamped, never thrown.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012hbFn24VWaxJBw8DUWjAmU

* chore(#4294): set changeset fragment pr to 4473

* docs(#4294): correct the pre-fix inline call-site count to five

The kernel's doc comment said SIX call sites carried their own
`Math.round((percent / 100) * width)`. The base tree has five: three in
`commands.cts` plus one each in `gsd2-import.cts` and
`formatProgressMachineSegment`, the latter two using `/ 10` with the width
already substituted (`pct` and `clamped` respectively).

The six is #4294's count of consumers -- it counts `cmdStateUpdateProgress`
and `syncCore` separately, but #4231 had already routed both through
`formatProgressMachineSegment` (as it does `applyPostSyncPreservation`), so by
this branch's base they share one copy. The comment now states the tree's count
and records where the six comes from, so neither number reads as an error
later.

Comment-only; no behaviour change, and no change to compiled output.

---------

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
Co-authored-by: Tom Boucher <trekkie@nomorestars.com>

.changeset/brave-elks-glide.md

@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 4473
+---
+**A progress bar is full only at 100%** — every bar-drawing surface (`progress` in table and bar format, `stats`, `state update-progress`, the STATE.md progress line written by `state sync`, and the gsd2 import writer) now draws through one render kernel, `renderProgressBar`, beside the completion-ratio kernel in `phase-lifecycle`. The six inline copies of `Math.round((percent / 100) * width)` each rounded to a full bar before the percent reached 100: at the 10-cell width every percent from 95 up drew `[██████████]`, at the 20-cell width every percent from 98 up, so a project at 19/20 plans was visually indistinguishable from a shipped one beside a number that said otherwise. Below 100 the fill is now held one cell short; only those percents move (95-99 at width 10, 98-99 at width 20), every other value in 0-100 renders exactly as before. A null or non-finite percent still renders an empty bar, and an out-of-range percent is clamped instead of throwing `RangeError` from `'░'.repeat` as the inline form did at 120%.