Implement Platform One Dark Theme for Compliance Dashboard

Description: Integrate Platform One’s dark-only theme across the Compliance Dashboard using the Tailwind + CSS variable configuration below.

• Background: #1F2220
• Accent: #6FD19C
• Dark-only mode (no light mode support)
• Variables and classes defined for easy reuse and extension.

Acceptance Criteria:

• All pages follow dark theme palette.
• Components use new theme utilities.
• UI meets WCAG AA contrast guidelines.
• No regressions in responsiveness or component behavior.

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