refactor(frontend): ic-token.validation -> schema (#3359)

# Motivation

As discussed offline in the context of #3357. We actually adopt a new
convention in which Zod schema related are provided in sub-folder
`schema`.

This prevents the introduction of circular dependencies when the
validation uses both types and Zod schema.

# Changes

- Rename `ic-token.validation` to `ic-token.schema`

src/frontend/src/icp/types/ic-token.ts

@@ -10,7 +10,7 @@ import {
 	IcInterfaceSchema,
 	IcTokenSchema,
 	IcTokenWithoutIdSchema
-} from '$icp/validation/ic-token.validation';
+} from '$icp/schema/ic-token.schema';
 import type { Option } from '$lib/types/utils';
 import { z } from 'zod';
 

src/frontend/src/tests/icp/validation/ic-token.validation.spec.ts → src/frontend/src/tests/icp/schema/ic-token.schema.spec.ts

@@ -16,10 +16,10 @@ import {
 	IcInterfaceSchema,
 	IcTokenSchema,
 	IcTokenWithoutIdSchema
-} from '$icp/validation/ic-token.validation';
+} from '$icp/schema/ic-token.schema';
 import { parseTokenId } from '$lib/validation/token.validation';
 
-describe('Schema Validation Tests', () => {
+describe('ic-token.schema', () => {
 	const { chainId: _, explorerUrl: __, ...mockNetwork } = SEPOLIA_NETWORK;
 
 	const mockToken = {