Upload: timeout + retry + ne ustavi loop ob enem fail-u

User: 'zakaj se je ustavilo? Naložil sem več kot 70.'

Diagnoza: 12/70+ je prišlo do server-ja (vsi 200 OK).
Browser-side problem: en upload je stuck → cel for-loop blokiran.

Fixes:
1. xhr.timeout = 10min per file (prej: večnost)
2. xhr.ontimeout, xhr.upload.ontimeout — proper error handling
3. NEW: uploadFileWithRetry() — 2x retry z 2s/4s eksponentnim delay-om
   za očasne mrežne odpovedi
4. Catch v loop ne kliče liveFail() (kar bi naredil disabled submit-btn)
   ampak samo showLive() z 'preskočil' sporočilo → loop nadaljuje
5. Console.warn v retry attempts za debugging

Sedaj če eno failes:
- Retry 2x avtomatsko (2s + 4s delay)
- Če še vedno ne uspe → preskoči to datoteko, nadaljuj z naslednjo
- Pri koncu vidiš katere so failed (v console + showLive)

templates/index.html

@@ -843,7 +843,7 @@
             fd.append("batch_id", batchId);
             
             try {
-              const uploadResp = await uploadFileXHR(fd, (loaded, total) => {
+              const uploadResp = await uploadFileWithRetry(fd, (loaded, total) => {
                 const filePct = (loaded / total) * 100;
                 showLive(
                   `Nalaganje ${i + 1}/${totalFiles}`,
@@ -861,8 +861,12 @@
               });
             } catch (e) {
               console.error(`Failed to upload ${f.name}: ${e.message}`);
-              liveFail(`Napaka pri ${f.name}: ${e.message}`);
-              // Continue z naslednjimi
+              showLive(
+                `⚠ Preskočil ${i + 1}/${totalFiles}`,
+                `${f.name}: ${e.message} (nadaljujem z naslednjim)`,
+                ((i + 1) / totalFiles) * 100
+              );
+              // Continue z naslednjimi (ne breakaj cel loop)
             }
           }
           
@@ -887,6 +891,8 @@
     function uploadFileXHR(formData, onProgress) {
       return new Promise((resolve, reject) => {
         const xhr = new XMLHttpRequest();
+        // 10 min timeout per file (za velike komade)
+        xhr.timeout = 10 * 60 * 1000;
         xhr.upload.onprogress = e => {
           if (e.lengthComputable && onProgress) {
             onProgress(e.loaded, e.total);
@@ -896,13 +902,33 @@
           if (xhr.status === 200) resolve(xhr.responseText);
           else reject(new Error(`HTTP ${xhr.status}: ${xhr.responseText.slice(0, 200)}`));
         };
-        xhr.onerror = () => reject(new Error("Upload error"));
+        xhr.onerror = () => reject(new Error("Network error (offline?)"));
+        xhr.ontimeout = () => reject(new Error("Timeout (10min)"));
         xhr.upload.onerror = () => reject(new Error("Upload transfer error"));
+        xhr.upload.ontimeout = () => reject(new Error("Upload timeout"));
         xhr.open("POST", "/api/upload");
         xhr.send(formData);
       });
     }
     
+    // Retry helper: če upload faila, poskusi 2x ponovno z malim delay-om
+    async function uploadFileWithRetry(formData, onProgress, maxRetries = 2) {
+      let lastErr = null;
+      for (let attempt = 0; attempt <= maxRetries; attempt++) {
+        try {
+          return await uploadFileXHR(formData, onProgress);
+        } catch (e) {
+          lastErr = e;
+          console.warn(`Upload attempt ${attempt + 1} failed: ${e.message}`);
+          if (attempt < maxRetries) {
+            // Eksponentni delay: 2s, 4s
+            await new Promise(r => setTimeout(r, 2000 * (attempt + 1)));
+          }
+        }
+      }
+      throw lastErr;
+    }
+
     // ─── Watch job (SSE) ────────────────────────────
     function watchJob(jobId) {
       const evt = new EventSource(`/api/stream/${jobId}`);