sync file-type support across upload/convert and fix collected_at timezone handling

internal/server/file_support_test.go

@@ -0,0 +1,17 @@
+package server
+
+import "testing"
+
+func TestIsSupportedConvertFileName_AcceptsNvidiaBugReportGzip(t *testing.T) {
+	if !isSupportedConvertFileName("nvidia-bug-report-1651124000923.log.gz") {
+		t.Fatalf("expected .log.gz bug-report to be supported")
+	}
+}
+
+func TestAnalyzeUploadedFile_RejectsUnsupportedExtension(t *testing.T) {
+	s := &Server{}
+	_, _, _, err := s.analyzeUploadedFile("unsupported.bin", "application/octet-stream", []byte("abc"))
+	if err == nil {
+		t.Fatalf("expected unsupported archive error")
+	}
+}