Polish compact desktop headers

[thomaspblock]

Summary

• Compact the shared desktop chat header and make header icons, badges, huddle controls, and member actions monochrome.
• Align the header with global history controls when the sidebar is collapsed, including matching loading skeleton behavior.
• Apply the same blurred overlay header treatment and top offsets across channels, Home, Pulse, Agents, and Workflows.
• Restore desktop window chrome behavior across the top header: larger drag target, no text cursor while dragging, and double-click to maximize.
• Tighten the right-side header padding so action buttons sit closer to the window edge.

Test plan

• cd desktop && pnpm check
• Pre-commit hooks on header layout commits
• Pre-push hooks via git push
• Merge latest origin/main into header-layout
• Smoke the channel, Home, Pulse, Agents, and Workflows headers in the desktop app with sidebar expanded and collapsed.
• Smoke window drag and double-click maximize from the top header area.

Made with Cursor

[thomaspblock]

header.mp4

[wesbillman]

@thomaspblock it looks like this new header breaks the window dragging and double click to go full screen, wanna take a look at those issues?

[thomaspblock]

🤖 Updated this PR with the header chrome fixes from the latest pushed commits:

• Added a larger top drag target for moving the window.
• Restored double-click maximize across the top header area.
• Prevented the text/I-beam cursor from appearing over draggable header text.
• Tightened the right-side header padding so the actions sit closer to the edge.
• Merged latest origin/main into header-layout.

Local/pre-push checks passed.

[thomaspblock]