revert: remove pin feature (rethinking approach)

[Gabko14]

Reverting #62 — the pin button approach is wrong. Need to rethink from first principles.

[claude]

Review

This revert PR cleanly removes the pin feature introduced in #62. The changes look correct:

What's being reverted:

• isPinned property removed from AppState (including UserDefaults persistence)
• Pin button UI removed from HeaderView
• Local MenuBarExtraAccess package fork deleted (1,100+ lines)
• Returns to upstream MenuBarExtraAccess package from orchetect/MenuBarExtraAccess

Code quality observations:

1. Clean revert — All pin-related code paths are properly removed. No orphaned references.

2. HeaderView signature simplified — Changed from taking AppState to just SettingsManager, which is a better pattern (only pass what's needed.

3. Package.resolved regenerated — The remote dependency is properly configured with requirement starting at 1.0.0.

4. No leftover UserDefaults — Note that may still exist in users' UserDefaults from fix: keep window open when pinned #62, but this is harmless (orphaned key, no cleanup needed).

Suggestion for future implementation:
The original approach of forking the upstream package to add behavior is a maintenance burden. When revisiting this feature, consider:

• Opening an upstream PR to with the functionality
• Using SwiftUI's native window management if available in newer macOS versions
• Implementing a standalone NSWindow approach instead of modifying the panel behavior

LGTM — straightforward revert with no issues.
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