fix: resolve startup loading stall for direct messages

[gabrielfordevelopment]

closes #41

On startup, the app could get stuck in an infinite loading state (most noticeably in direct message routes) until navigating away and back.

• Fixed startup loading stall when opening chat routes from cached destinations
• Added fallback channel resolution from API when channel cache is not ready
• Prevented app startup gate from blocking indefinitely on login error paths
• Avoided writing drafts to an invalid draftContent/null key during channel switch

Kept changes focused to startup navigation and chat draft persistence behavior.

Currently we have this:

1000017599.mp4

What I made have this:

1000017596.mp4