Keep brightness OSD popup width uniform across all percentages (#5806)

Pad the percent text to 3 chars with printf so "  5%", " 50%", and
"100%" render at identical width in the JetBrainsMono monospace label.
Previously the popup container resized between events because the
label string varied between 2 and 4 characters, which caused the
popup to visibly jump in width on consecutive brightness key presses.

Builds on #5525, which made the percent values themselves step
uniformly; this completes the loop by making the rendered popup match.

Co-authored-by: Mateus Pegorim <14262063+Pegorim@users.noreply.github.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

bin/omarchy-swayosd-brightness

@@ -12,4 +12,4 @@ progress="$(awk -v p="$percent" 'BEGIN{printf "%.2f", p/100}')"
 omarchy-swayosd-client \
   --custom-icon display-brightness-symbolic \
   --custom-progress "$progress" \
-  --custom-progress-text "${percent}%"
+  --custom-progress-text "$(printf '%3d%%' "$percent")"