style: make MaxShardCount type casting explicit in loops

Improved code clarity by explicitly casting MaxShardCount to the
appropriate type when used in loop comparisons:

- ShardId comparisons: Cast to ShardId(MaxShardCount)
- uint32 comparisons: Cast to uint32(MaxShardCount)

Changed in 5 locations:
- Minus() loop (line 90)
- ShardIds() loop (line 143)
- ToUint32Slice() loop (line 152)
- IndexToShardId() loop (line 219)
- resizeShardSizes() loop (line 248)

This makes the intent explicit and improves type safety readability.
No functional changes - purely a style improvement.

weed/storage/erasure_coding/ec_volume_info.go

@@ -87,7 +87,7 @@ func (ecInfo *EcVolumeInfo) Minus(other *EcVolumeInfo) *EcVolumeInfo {
 
 	// Copy shard sizes for remaining shards
 	retIndex := 0
-	for shardId := ShardId(0); shardId < MaxShardCount && retIndex < len(ret.ShardSizes); shardId++ {
+	for shardId := ShardId(0); shardId < ShardId(MaxShardCount) && retIndex < len(ret.ShardSizes); shardId++ {
 		if ret.ShardBits.HasShardId(shardId) {
 			if size, exists := ecInfo.GetShardSize(shardId); exists {
 				ret.ShardSizes[retIndex] = size
@@ -140,7 +140,7 @@ func (b ShardBits) HasShardId(id ShardId) bool {
 }
 
 func (b ShardBits) ShardIds() (ret []ShardId) {
-	for i := ShardId(0); i < MaxShardCount; i++ {
+	for i := ShardId(0); i < ShardId(MaxShardCount); i++ {
 		if b.HasShardId(i) {
 			ret = append(ret, i)
 		}
@@ -149,7 +149,7 @@ func (b ShardBits) ShardIds() (ret []ShardId) {
 }
 
 func (b ShardBits) ToUint32Slice() (ret []uint32) {
-	for i := uint32(0); i < MaxShardCount; i++ {
+	for i := uint32(0); i < uint32(MaxShardCount); i++ {
 		if b.HasShardId(ShardId(i)) {
 			ret = append(ret, i)
 		}
@@ -216,7 +216,7 @@ func (b ShardBits) IndexToShardId(index int) (shardId ShardId, found bool) {
 	}
 
 	currentIndex := 0
-	for i := ShardId(0); i < MaxShardCount; i++ {
+	for i := ShardId(0); i < ShardId(MaxShardCount); i++ {
 		if b.HasShardId(i) {
 			if currentIndex == index {
 				return i, true
@@ -245,7 +245,7 @@ func (ecInfo *EcVolumeInfo) resizeShardSizes(prevShardBits ShardBits) {
 	// Copy existing sizes to new positions based on current ShardBits
 	if len(ecInfo.ShardSizes) > 0 {
 		newIndex := 0
-		for shardId := ShardId(0); shardId < MaxShardCount && newIndex < expectedLength; shardId++ {
+		for shardId := ShardId(0); shardId < ShardId(MaxShardCount) && newIndex < expectedLength; shardId++ {
 			if ecInfo.ShardBits.HasShardId(shardId) {
 				// Try to find the size for this shard in the old array using previous ShardBits
 				if oldIndex, found := prevShardBits.ShardIdToIndex(shardId); found && oldIndex < len(ecInfo.ShardSizes) {