Fix MiniMax API fetch region

[theglove44]

Problem

MiniMax API usage fetches always target api.minimaxi.com, even when the provider is configured for the global (.io) stack. For sk-cp- keys tied to .io, this results in MiniMax credentials are invalid or expired. In the UI, MiniMax shows minimax.api (api) available error=MiniMax credentials are invalid or expired. and minimax.web (web) unavailable, which then surfaces No available fetch strategy for minimax.

Investigation

• MiniMaxUsageFetcher hard-coded https://api.minimaxi.com/v1/api/openplatform/coding_plan/remains.
• The MiniMax region setting is used for web requests but not the API token path.
• With a .io key, the API request is sent to the .com host and fails authentication.

Example (debug pane):

• minimax.api (api) available error=MiniMax credentials are invalid or expired.
• minimax.web (web) unavailable
• Menu card: No available fetch strategy for minimax.

Proposed solution

• Add region-aware API base URLs (api.minimax.io vs api.minimaxi.com).
• Use the region’s API base when fetching coding plan remains.
• Pass the MiniMax region from settings into the API fetch strategy.

Changes

• MiniMaxAPIRegion adds apiBaseURLString and apiRemainsURL.
• MiniMaxUsageFetcher.fetchUsage(apiToken:) now uses region.apiRemainsURL.
• MiniMaxAPIFetchStrategy passes the configured region into the API fetcher.

Testing

• ./Scripts/compile_and_run.sh failed on this machine due to Swift toolchain/SDK mismatch (SwiftBridging redefinition; SDK built with a different Swift version).
• pnpm check failed because swiftformat is not installed on PATH.