Badge Comparison: anafanafo vs pretext

Why snapshots changed

This PR replaces anafanafo with @chenglou/pretext for text width measurement in badge generation. The two libraries measure text width slightly differently, which causes some snapshot values to change.

Summary of all snapshot changes

Category	Count	SVG width diff	Cause
flat, flat-square, plastic templates	0	0px	No change — pretext + `preferredWidthOf()` produces identical results to anafanafo for Verdana 11px
for-the-badge template	0	0px	No change — letter-spacing compensation already in place, pretext matches anafanafo for Verdana 10px
social template (with label text)	All	0px	No change — pretext text widths match anafanafo for Helvetica bold 11px with the current social badge renderer
social template (empty label)	4	-1px	Empty string: anafanafo returned width 10 (1px), pretext returns 0. See details below.

Root cause: empty string width

The only difference comes from the empty string edge case. When measuring an empty label (""):

anafanafo("") returned 10 (i.e., 1px after scale(.1)), which was then rounded up to 11 by roundUpToOdd().
pretext returns 0 for an empty string, which is the correct behavior — an empty string has no width.

This 1px difference cascades into the SVG: the label rect shrinks by 1px, and all downstream x-coordinates shift accordingly.

Why the pretext behavior is correct

An empty string should have zero width. The old anafanafo value of 10 (1px) was a quirk of how anafanafo handled the empty-string case. The new pretext value of 0 produces a more accurate badge — there is no visible difference since the label text is empty anyway.

Affected snapshots (4 total)

The only differences are in the 4 snapshots with empty labels. These show a 1px width reduction due to the empty string width change.

Snapshot	Old width	New width	textLength change
"social" message only, no logo	59px	58px	10 → 0
"social" message only, with logo	73px	72px	10 → 0
"social" message only, with logo and labelColor	73px	72px	10 → 0
"social" logo-only	26px	25px	10 → 0

Width alignment notes

pretext measures raw glyph widths. Only the for-the-badge template still needs explicit letter-spacing compensation to match the previous anafanafo measurements:

social template: current width calculation matches anafanafo for Helvetica bold 11px
for-the-badge template: LETTER_SPACING = 1.25 per character for Verdana 10px
flat / flat-square / plastic: no compensation needed — preferredWidthOf() already matches anafanafo for Verdana 11px

Visual comparisons: social template (with label text)

pretext produces identical text widths to anafanafo for non-empty social badge labels. The badge appearance is the same.

message/label, no logo

message only, no logo (empty label edge case)

Visual comparisons: empty label snapshots (diff > 1px in inner attributes)

These 4 snapshots are the only ones with any difference. The root cause is that anafanafo("") returned 10 while pretext correctly returns 0 for empty strings. This causes a 1px SVG width reduction and shifts internal x-coordinates by up to 10 units (1px at scale(.1)).