refactor(client): migrate deprecated Ant Design v6 APIs

[apalchys]

Motivation

• Bring client codebase in line with Ant Design v6 API surface after migration to remove deprecated props and avoid runtime breakage.
• Standardize modal and layout prop usage across shared components and pages to follow the new open/styles/variant conventions.

Description

• Replace visible -> open for modal wrappers and their callers, including CommentModal, StudentMentorModal, and all discovered usages in page components so modals use open consistently.
• Replace deprecated style props: change bordered={false} -> variant="borderless" and convert bodyStyle/headStyle/overlayStyle -> styles={{ body: {...} }} or styles={{ header: {...} }} where applicable in Card, Table, Popover, and Modal usages across client/src.
• Applied the pattern-based updates across a sweep of UI components and pages under client/src (shared components, modules, and pages) to remove v5-style props and align with v6 API shapes.

[AlreadyBored]

@apalchys E2E tests fail because of this

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