* fix(popup): keep usage percentages flush with their meters

The hover-revealed hide button in a provider usage row sat after the
percentage. At opacity 0 it still reserved its layout width, so every
percentage ended about 30 pixels short of the meter's right edge.

Place the button before the percentage so its reserved space falls in
the existing gap after the row label. Add a QtTest that pins the
percentage's trailing edge to the meter's.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

* docs(changelog): note percentage alignment in the hide-row entry

Revise the unreleased hide-row entry instead of adding a Fixed entry: the
misalignment came with that unreleased feature and never shipped.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

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Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>