feat(provider): refresh and update providers

[tarik02]

Problem

Provider model data can become stale after authentication, configuration, or installation changes. T3 Code can reprobe providers and update their installed CLIs, but t3cli exposes neither operation.

Scope

Add provider maintenance commands for:

• Refreshing all configured provider instances.
• Refreshing one provider instance.
• Updating a provider installation, optionally targeting an instance where supported.

Use server.refreshProviders and server.updateProvider.

Safety

Provider updates change software on the target environment. Require interactive confirmation and support the standard non-interactive confirmation flag.

Acceptance criteria

• Refresh returns the refreshed provider snapshot.
• Update reports whether the provider changed and returns the refreshed provider snapshot.
• Instance selection uses provider instance IDs, not display labels.
• Authorization and provider update failures remain structured CLI errors.