Change theme logic to prioritize dark mode

[leecalcote]

Updated color mode logic to prioritize light mode when active.

Description

1. Honor System: We keep the default setting as SYSTEM.
2. Dark as Default: We invert the check. Instead of asking "Is it Dark?", we ask "Is it Light?". If the system explicitly asks for Light, we give them Light. For everything else (Dark preference, No preference, or unsupported browsers), we default to Dark.
3. Dark Fallback: We update the default error case.

Signed commits

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