refactor(auth): integrate Hono's JWT middleware and expand payload info

[ZL-Asica]

• Replaced custom validateAuthToken logic in auth-token with Hono's JWT middleware for streamlined token validation and decoding.

• Expanded JWT payload to include username and created_at fields for better reusability, reducing the need for repetitive database calls.

• Updated auth-middleware to handle decoded payload, simplifying data access.

• Future improvements: Consider implementing payload refresh within the middleware to optimize database access frequency.

[github-actions[bot]]

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