Fix zero value parsing in SVG paths (resolves #228)

This commit fixes a bug where zero values in SVG path definitions were
incorrectly ignored when followed by whitespace and a decimal number.
For example, "0 0 0 .25" was being parsed as "0" "0" "0.25" instead of
the correct "0" "0" "0" "0.25".

The root cause was that the scanner's charactersToBeSkipped included all
whitespace, causing "0 .25" to be recognized as a single number "0.25".

Changes:
- Limited scanner.charactersToBeSkipped to only newlines (not all whitespace)
- Added explicit whitespace handling in the operand parsing loop
- This ensures zero values are correctly recognized as discrete operands

The fix ensures that the testPathValuesWithLeadingZeros test passes,
which verifies that shortcut SVG notations like "M 00.01 a 2 1 0 006 0"
parse correctly to match their expanded equivalents.

Author: claude

Sources/SVGEngine.mm

@@ -547,7 +547,7 @@ CGPathRef CGPathFromSVGPathString(NSString *svgString) {
     dispatch_once(&onceToken, ^{
         commands   = [NSCharacterSet characterSetWithCharactersInString:kValidSVGCommands];
         separators = [NSMutableCharacterSet characterSetWithCharactersInString:@","];
-        [(NSMutableCharacterSet *)separators formUnionWithCharacterSet:NSCharacterSet.whitespaceAndNewlineCharacterSet];
+        [(NSMutableCharacterSet *)separators formUnionWithCharacterSet:NSCharacterSet.newlineCharacterSet];
     });
     scanner.charactersToBeSkipped = separators;
 
@@ -558,6 +558,9 @@ CGPathRef CGPathFromSVGPathString(NSString *svgString) {
             scanner.scanLocation -= [cmdBuf length]-1;
         } else {
             while (!scanner.isAtEnd) {
+                // Explicitly skip whitespace
+                while ([scanner scanCharactersFromSet:[NSCharacterSet whitespaceCharacterSet] intoString:NULL]) { }
+
                 NSUInteger zeros = 0;
                 while ([scanner scanString:@"0" intoString:NULL]) { ++zeros; }
                 // Start of a 0.x ?