[Icons] Add a sticker icon treatment

The pre-#7595 add, remove and delete icons were filled shapes with a black
outline and no disc. A tint cannot bring that back, and the badge disc is a
different icon language, so add a third value to the existing style axis.

IconStyle::Sticker draws the sentinel glyph twice: a near-black rim at the
band width plus one rim on each side, then the tone pass clipped to the glyph
and filled with a vertical gradient. Both treatments keep the disabled
fallback to the line glyph.

The fill rule moves into theme_icon_fill: the semantic tones are tuned for
text, so a filled shape gives its tone a saturation floor, and a dark-scheme
tone is pulled down rather than up. IconTint::resolve() applies the same floor
to line glyphs, and the badge disc uses the same fill, so a line, a badge and
a sticker next to each other carry the same green or red instead of a pale
line beside a saturated glyph.

The badge's glyph ink follows the scheme: white on light-scheme tones, as in
the pre-#7595 art, and the saturated tone darkened to an outline-dark ink on
dark-scheme tones, where the shared saturated disc is light enough that white
would sit near 2.7:1. The new test pins both cases so the glyph cannot
silently flip.

resolveSvgStrokeWidth() moves the stroke-width rewrite into
libcockatrice_utility so the badge and the sticker share it; the badge's local
copy is gone.

The sticker is opted into at 17 call sites: increment, decrement and
remove_row in the deck editor, settings pages, token dialog, server dialogs
and replay/deck storage tabs. The visual database's clear-filter button keeps
its trash can (icons/delete) in the line treatment: that glyph is new in
#7595, but it is the clearer metaphor, and a sticker rim closes its lid gap
at toolbar sizes.

The preview generators also gain a semantic-tint sheet for #7775 and a
line/badge/sticker family strip, so the three PR descriptions can show the
same rendered colors.

libcockatrice_utility/libcockatrice/utility/svg_recolor.cpp

@@ -42,3 +42,46 @@ QByteArray resolveSvgColorSentinel(const QByteArray &svg, const QByteArray &colo
     }
     return resolved;
 }
+
+QByteArray resolveSvgStrokeWidth(const QByteArray &svg, double width)
+{
+    constexpr QByteArrayView ATTRIBUTE = "stroke-width";
+    constexpr QByteArrayView DOUBLE_QUOTE = "\"";
+    constexpr QByteArrayView SINGLE_QUOTE = "'";
+    const QByteArray value = QByteArray::number(width, 'f', 2);
+
+    QByteArray resolved;
+    resolved.reserve(svg.size());
+
+    qsizetype cursor = 0;
+    while (true) {
+        const qsizetype start = svg.indexOf(ATTRIBUTE, cursor);
+        if (start < 0) {
+            resolved.append(svg.sliced(cursor));
+            return resolved;
+        }
+
+        // Only an XML attribute is rewritten. A CSS declaration such as
+        // `style="stroke-width:2"` has no `=` right after the name, so it stays
+        // untouched and the scan moves past it.
+        qsizetype nameEnd = start + ATTRIBUTE.size();
+        while (nameEnd < svg.size() && svg.at(nameEnd) == ' ') {
+            ++nameEnd;
+        }
+        const bool isAttribute = nameEnd < svg.size() && svg.at(nameEnd) == '=' && nameEnd + 1 < svg.size();
+        const char quoteChar = isAttribute ? svg.at(nameEnd + 1) : '\0';
+        const bool quoted = quoteChar == '"' || quoteChar == '\'';
+        const qsizetype close = quoted ? svg.indexOf(quoteChar == '"' ? DOUBLE_QUOTE : SINGLE_QUOTE, nameEnd + 2) : -1;
+        if (close < 0) {
+            resolved.append(svg.sliced(cursor, start + ATTRIBUTE.size() - cursor));
+            cursor = start + ATTRIBUTE.size();
+            continue;
+        }
+
+        // Keep the opening quote, replace the value, and resume at the closing
+        // quote so the rest of the document is copied verbatim.
+        resolved.append(svg.sliced(cursor, nameEnd + 2 - cursor));
+        resolved.append(value);
+        cursor = close;
+    }
+}

libcockatrice_utility/libcockatrice/utility/svg_recolor.h

@@ -28,4 +28,21 @@
  */
 QByteArray resolveSvgColorSentinel(const QByteArray &svg, const QByteArray &color);
 
+/**
+ * @brief Rewrites the value of every `stroke-width` attribute in authored SVG.
+ *
+ * A treatment can need a heavier or lighter stroke than the one authored for a
+ * line icon at text size. Like the sentinel resolver, this rewriter works on the
+ * bytes and understands only the XML attribute form, in either quote style
+ * (`stroke-width="2"` or `stroke-width='2'`): a CSS declaration such as
+ * `style="stroke-width:2"` is left untouched. Documents without the attribute
+ * are returned unchanged.
+ *
+ * @param svg SVG source bytes, expected to be UTF-8. Invalid UTF-8 is preserved
+ *            byte-for-byte.
+ * @param width Replacement width in the document's user units.
+ * @return The rewritten SVG source; the input is left untouched.
+ */
+QByteArray resolveSvgStrokeWidth(const QByteArray &svg, double width);
+
 #endif // SVG_RECOLOR_H