fix: align first GPT partition entry to 1024 sectors

With 512 sector size, first usable LBA is aligned to 2048 already, but
with 4096 sector size, the calculation would end up with 256.

To provide better compatibility with some firmware, make it start at
sector 1024 minimum.

See siderolabs/talos#10097

Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>

partitioning/gpt/gpt.go

@@ -262,10 +262,11 @@ func (t *Table) init(lastLBA uint64) {
 		ioSize = t.sectorSize
 	}
 
-	alignmentSize := max(ioSize, 2048*512)
-	t.alignment = uint64((alignmentSize + t.sectorSize - 1) / t.sectorSize)
+	alignmentSize := max(ioSize, 1048576)                                   // align to 1Mib minimum
+	t.alignment = uint64((alignmentSize + t.sectorSize - 1) / t.sectorSize) // 2048 with 512 sector size, 256 with 4096 sector size
 
-	t.firstUsableLBA = (t.firstUsableLBA + t.alignment - 1) / t.alignment * t.alignment
+	t.firstUsableLBA = (t.firstUsableLBA + t.alignment - 1) / t.alignment * t.alignment // 2048 with 512 sector size, 256 with 4096 sector size
+	t.firstUsableLBA = max(t.firstUsableLBA, 1024)                                      // make first usable LBA at least 1024 to avoid issues with some BIOSes
 }
 
 // Clear the partition table.