Create consistent global header with quick settings accessible from all key screens

[Yashb404]

Summary

A consistent header with quick settings is missing, reducing discoverability of global actions and causing navigation inconsistency.

Current Behavior

• Header patterns vary by screen.
• Quick settings/access controls are not consistently available.

Expected Behavior

• One shared header pattern across dashboard/editor/docs/user where appropriate.
• Quick settings always easy to access.
• Consistent placement of profile, theme, and utility actions.

Scope

• Define global header component and variants by context.
• Add quick settings entry with consistent interaction model.
• Standardize placement for search, guide/logs, profile/settings.
• Ensure mobile and desktop responsive behavior is coherent.

Acceptance Criteria

• Shared header is used across key screens.
• Quick settings are reachable in <=1 click/tap.
• Header behavior remains consistent across route transitions.
• Responsive layouts preserve usability and clarity.