fix(tui): resolve wrong provider prefix when session has model without modelProvider (#25874)

Merged via /review-pr -> /prepare-pr -> /merge-pr.

Prepared head SHA: f0953a7284
Co-authored-by: lbo728 <72309817+lbo728@users.noreply.github.com>
Co-authored-by: gumadeiras <5599352+gumadeiras@users.noreply.github.com>
Reviewed-by: @gumadeiras

src/gateway/server-methods/sessions.ts

@@ -387,6 +387,7 @@ export const sessionsHandlers: GatewayRequestHandlers = {
         reasoningLevel: entry?.reasoningLevel,
         responseUsage: entry?.responseUsage,
         model: entry?.model,
+        modelProvider: entry?.modelProvider,
         contextTokens: entry?.contextTokens,
         sendPolicy: entry?.sendPolicy,
         label: entry?.label,