ZK-1337: simplify directory layout & remove console logs

[kroist]

• remove ./shielder folder, as everything is in "shielder" domain
• add index.ts to every folder module, and list exports in it instead of exports in separate files.
• remove console.error logs, as we throw exceptions instead.

[github-actions]

Transaction Name	Main	Current	Difference (%)
NewAccountNative	2000335	2000359	+0.00120%
DepositNative	1827894	1827930	+0.00197%
WithdrawNative	1898162	1898162	0.00000%

[github-actions]

📊 Coverage Report

📈 Total Coverage Summary

Type	Covered	Total	Coverage
📝 Lines	142	403	❌ 35.23%
📄 Statements	143	406	❌ 35.22%
⚡ Functions	38	105	❌ 36.19%
🔀 Branches	14	66	❌ 21.21%

Coverage Legend

• ✅ 100% Coverage
• 🟡 80-99% Coverage
• 🟠 50-79% Coverage
• ❌ 0-49% Coverage

📁 File Coverage

📋 Detailed Coverage Report

File	Lines	Statements	Functions	Branches
✅ zkOS-monorepo/ts/shielder-sdk/src/actions/deposit.ts	100%	100%	100%	100%
✅ zkOS-monorepo/ts/shielder-sdk/src/actions/newAccount.ts	100%	100%	100%	100%
✅ zkOS-monorepo/ts/shielder-sdk/src/actions/utils.ts	100%	100%	100%	100%
✅ zkOS-monorepo/ts/shielder-sdk/src/actions/withdraw.ts	100%	100%	100%	100%
❌ zkOS-monorepo/ts/shielder-sdk/src/chain/contract.ts	4.76%	4.76%	7.14%	0%
❌ zkOS-monorepo/ts/shielder-sdk/src/chain/relayer.ts	8.57%	8.57%	14.28%	0%
❌ zkOS-monorepo/ts/shielder-sdk/src/client.ts	0%	0%	0%	0%
✅ zkOS-monorepo/ts/shielder-sdk/src/constants.ts	100%	100%	100%	100%
❌ zkOS-monorepo/ts/shielder-sdk/src/state/events.ts	0%	0%	0%	0%
❌ zkOS-monorepo/ts/shielder-sdk/src/state/manager.ts	0%	0%	0%	0%
❌ zkOS-monorepo/ts/shielder-sdk/src/state/storageSchema.ts	0%	0%	0%	0%
❌ zkOS-monorepo/ts/shielder-sdk/src/state/sync.ts	0%	0%	0%	0%
✅ zkOS-monorepo/ts/shielder-sdk/src/utils.ts	100%	100%	100%	100%