feat: Decode variable wind between two headings

Co-authored-by: aider (gemini/gemini-2.5-pro) <aider@aider.chat>

metar.html

@@ -98,6 +98,11 @@
             return text;
         }
 
+        function decodeVariableWind(code) {
+            const [dir1, dir2] = code.split('V');
+            return `${code}: Wind variable between ${dir1}° and ${dir2}°`;
+        }
+
         function decodeVisibility(code) {
             const vis = code.replace('SM', '');
             return `${code}: Visibility ${vis} statute miles`;
@@ -579,6 +584,8 @@
 
                 if (part.endsWith('KT')) {
                     sections.push({ raw: part, decoded: decodeWind(part) });
+                } else if (part.match(/^\d{3}V\d{3}$/)) {
+                    sections.push({ raw: part, decoded: decodeVariableWind(part) });
                 } else if (part.endsWith('SM') || part.match(/^\d+$/)) {
                     sections.push({ raw: part, decoded: decodeVisibility(part) });
                 } else if (part.match(/^([+-]|VC)?(MI|PR|BC|DR|BL|SH|TS|FZ|DZ|RA|SN|SG|IC|PL|GR|GS|UP|BR|FG|FU|VA|DU|SA|HZ|PY|PO|SQ|FC|SS|DS|TR)+$/)) {