feat: track upstream request ID and prevent response header override

When proxying through another new-api instance, the upstream
X-Oneapi-Request-Id was overwriting the local one in client responses.
This adds a new `upstream_request_id` field to the logs table, captures
the upstream ID during relay, and filters it from being copied back to
the client. Frontend gains search/filter and detail display support.

web/default/src/features/usage-logs/data/schema.ts

@@ -44,6 +44,7 @@ export const usageLogSchema = z.object({
   ip: z.string().default(''),
   other: z.string().default(''),
   request_id: z.string().default(''),
+  upstream_request_id: z.string().default(''),
 })
 
 export type UsageLog = z.infer<typeof usageLogSchema>