Show status indication when Publisher initiates background auth/API calls on startup

[m--]

When Publisher opens, it immediately begins loading credentials and making API calls (fetching available integrations, env vars for existing deployments, etc.) without the user explicitly initiating a deployment. With browser-based auth, this is particularly jarring because it can trigger a browser auth flow the user didn't expect.

Problem

• Users see unexpected browser popups for auth without understanding why
• If there's no internet connection, the sidebar may be inaccurate with no explanation
• No indication that Publisher is "doing something" in the background

Proposed solution

Show a status message or notification indicating that Publisher is performing setup/fetching server details. Some considerations:

• Showing a notification on every startup might be too noisy
• Could potentially show it only when browser-based auth is triggered
• VS Code has precedents for this (status bar messages, progress notifications)
• Need to balance informing users vs. being annoying

Open questions

• Should this only appear when browser auth is involved, or always?
• Status bar vs. notification vs. sidebar loading state?
• Should there be a way to defer/cancel the initial fetch?

[christierney]

While testing the caching/refreshing of snowflake tokens, I've seen a noticeable lag between clicking the deploy button and the deploy starting. I assume (it's hard to prove) that this is happening when the token expires and is being refreshed. So we might also want to have a status indication any time a credential is being loaded, not just at startup.