feat(giga): implement iterator for the cachekv

[arajasek]

Describe your changes and provide context

Since we need Giga to interoperate with v2, we need to return all balances for accounts that are being migrated. This PR implements the Iterator to do that.

If we don't want to implement Iterator on the cachekv, an alternative is to just squish the logic into GetAllBalances or SpendableCoins directly. That would look something like this:

// rangeStore is an interface for stores that support GetAllKeyStrsInRange
type rangeStore interface {
	GetAllKeyStrsInRange(start, end []byte) []string
	Get(key []byte) []byte
}

// GetAllBalances returns all the balances for a given account address.
func (k BaseViewKeeper) GetAllBalances(ctx sdk.Context, addr sdk.AccAddress) sdk.Coins {
	store := k.GetKVStore(ctx)
	accountPrefix := types.CreateAccountBalancesPrefix(addr)

	// Try to use GetAllKeyStrsInRange directly (avoids Iterator which may not be supported)
	if rs, ok := store.(rangeStore); ok {
		// Calculate end key for prefix range (prefix + 0xFF...)
		end := make([]byte, len(accountPrefix))
		copy(end, accountPrefix)
		for i := len(end) - 1; i >= 0; i-- {
			end[i]++
			if end[i] != 0 {
				break
			}
		}

		keyStrs := rs.GetAllKeyStrsInRange(accountPrefix, end)
		balances := sdk.NewCoins()
		for _, keyStr := range keyStrs {
			bz := rs.Get([]byte(keyStr))
			if bz != nil {
				var balance sdk.Coin
				k.cdc.MustUnmarshal(bz, &balance)
				balances = append(balances, balance)
			}
		}
		return balances.Sort()
	}

	// Fall back to standard iteration for non-GIGA stores
	accountStore := prefix.NewStore(store, accountPrefix)
	balances := sdk.NewCoins()
	iterator := accountStore.Iterator(nil, nil)
	defer iterator.Close()

	for ; iterator.Valid(); iterator.Next() {
		var balance sdk.Coin
		k.cdc.MustUnmarshal(iterator.Value(), &balance)
		balances = append(balances, balance)
	}

	return balances.Sort()
}

Testing performed to validate your change

[github-actions]

The latest Buf updates on your PR. Results from workflow Buf / buf (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Feb 27, 2026, 7:36 PM

[codecov]

Codecov Report

❌ Patch coverage is 31.11111% with 31 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.12%. Comparing base (7cfe94a) to head (b2cffcc).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
giga/deps/store/cachekv.go	0.00%	30 Missing ⚠️
giga/deps/xbank/keeper/view.go	93.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2994      +/-   ##
==========================================
- Coverage   58.12%   58.12%   -0.01%     
==========================================
  Files        2111     2111              
  Lines      173544   173583      +39     
==========================================
+ Hits       100879   100889      +10     
- Misses      63706    63735      +29     
  Partials     8959     8959              

Flag	Coverage Δ
sei-chain-pr	59.18% <31.11%> (?)
sei-db	69.50% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
giga/deps/xbank/keeper/view.go	92.98% <93.33%> (+1.49%)	⬆️
giga/deps/store/cachekv.go	42.01% <0.00%> (-13.54%)	⬇️

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