feat: add shared boolean query flag parser

[Benedict315]

Summary

Add a shared helper for parsing boolean-like query flags and apply it to creator list query parsing so boolean flags are handled consistently.

What Changed

• added a shared boolean query parser for true, false, 1, and 0
• added a Zod-friendly query helper for reusing that parser in endpoint schemas
• updated creator list query parsing to use the shared helper for verified
• aligned the standalone creator filter parser with the shared behavior
• added focused tests for valid values and consistent validation errors

Validation

• corepack pnpm exec jest src/utils/test/parseBoolean.utils.test.ts --runInBand
• corepack pnpm exec ts-node src/modules/creators/creators.filter.test.ts
• corepack pnpm exec ts-node src/modules/creators/creators.boolean-query.parse.test.ts
• corepack pnpm build

Notes

• invalid boolean-like query values now return a consistent validation error instead of silently coercing to false
• accepted values are now scoped to true / false / 1 / 0

closes #226

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