Release 2.7.3.1: harden proxy recovery, updates and local API.

Restore orphaned system proxy after crash, require update SHA-256, add macOS /api auth token, fix UDP ping false positives, HTTPS-only subscriptions, and keep the UI responsive during connect.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/sysproxy/sysproxy.go

@@ -7,6 +7,9 @@ type Controller interface {
 	Enable(httpHostPort string) error
 	Disable() error
 	Enabled() bool
+	// ForceDisable turns off proxy settings even if this process did not Enable them
+	// (used to recover after crash/kill when a sentinel file remains).
+	ForceDisable() error
 }
 
 // New returns a platform-specific controller.