fix(orm): add explicit PostgreSQL column types for all ORM entities
- user-service: user.orm.ts (lastActiveAt), verification-code.orm.ts (all fields)
- file-service: file.orm.ts (userId, originalName, storagePath, mimeType)
- conversation-service: token-usage.orm.ts (model, all token/count fields)
- knowledge-service: knowledge-article.orm.ts, knowledge-chunk.orm.ts,
system-experience.orm.ts, user-memory.orm.ts (all numeric, boolean, date fields)
This fixes DataTypeNotSupportedError where PostgreSQL rejects "Object" type
when @Column decorator lacks explicit type specification.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>