feat: Collect and report unknown METAR elements in test summary

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

metar.html

@@ -550,6 +550,13 @@
             let failed = 0;
             let withUnknowns = 0;
             const originalConsoleLog = console.log;
+            const unknowns = {
+                airports: new Set(),
+                weatherChunks: new Set(),
+                cloudInfos: new Set(),
+                cloudTypesInRemark: new Set(),
+                otherRemarks: new Set(),
+            };
 
             metars.forEach(metarString => {
                 const tempLogs = [];
@@ -567,7 +574,25 @@
                     if (hasUnknowns) {
                         withUnknowns++;
                         originalConsoleLog(`METAR with decoding issues: ${metarString}`);
-                        tempLogs.forEach(msg => originalConsoleLog(`  -> ${msg}`));
+                        tempLogs.forEach(msg => {
+                            originalConsoleLog(`  -> ${msg}`);
+                            if (msg.startsWith('Unknown Airport code:')) {
+                                const code = msg.split(' ')[3];
+                                unknowns.airports.add(code);
+                            } else if (msg.startsWith('Unknown weather chunk:')) {
+                                const chunk = msg.split(' ')[3];
+                                unknowns.weatherChunks.add(chunk);
+                            } else if (msg.startsWith('Unknown cloud information:')) {
+                                const code = msg.split(' ')[3];
+                                unknowns.cloudInfos.add(code);
+                            } else if (msg.startsWith('Unknown cloud type in remark:')) {
+                                const code = msg.split(' ')[5];
+                                unknowns.cloudTypesInRemark.add(code);
+                            } else if (msg.startsWith('Other remark:')) {
+                                const remark = msg.split(' ')[2];
+                                unknowns.otherRemarks.add(remark);
+                            }
+                        });
                     }
 
                 } catch (e) {
@@ -585,6 +610,14 @@
             console.log(`Clean decodes: ${clean} (${(clean/total*100).toFixed(1)}%)`);
             console.log(`Decodes with issues: ${withUnknowns} (${(withUnknowns/total*100).toFixed(1)}%)`);
             console.log(`Failed to parse: ${failed} (${(failed/total*100).toFixed(1)}%)`);
+
+            console.log(`\n--- Unknowns encountered ---`);
+            for (const key in unknowns) {
+                if (unknowns[key].size > 0) {
+                    console.log(`${key}:`);
+                    console.log([...unknowns[key]].sort());
+                }
+            }
         }
 
         testAllBtn.addEventListener('click', testAllMetars);