fix: filter sheet modal, form card width, and timezone label overflow on mobile

[gaghan430]

Summary

Follow-up fixes from the responsive mobile improvements (#409).

• Filter sheet: set modal={false} on the DataTableToolbar Sheet so portaled Radix dropdowns (SelectFilter options) receive clicks instead of being blocked by the modal overlay
• Form card width: Col span={12} offset={6} → Col xs={24} md={{ span: 12, offset: 6 }} so form cards use full width on mobile (5 pages: contact create/detail, contact-group create/detail, profile settings)
• Timezone select: wrap label in truncate span to prevent long timezone labels from overlapping the chevron icon

Test plan

• Filter sheet: open filter → tap dropdown option → value selects correctly (users, organizations, fraud, email, activity pages)
• Form pages at mobile width: /contacts/create, /contact-groups/create, /profile → card fills viewport
• Timezone select at /profile: selected label truncates with ellipsis, chevron visible
• Desktop: all pages unchanged

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