feat: add MiniMax quota fetcher and brand icon (#1662)

* feat(server): add MiniMax quota fetcher

Mirror the live multi-provider quota panel (#1278) for MiniMax. Resolves the
bearer token from $MINIMAX_API_KEY or the MiniMax CLI config at
~/.mmx/config.json (api_key, oauth.access_token) and credentials at
~/.mmx/credentials.json, then queries the /v1/token_plan/remains endpoint on
the configured region (global by default, cn when region='cn'). The response
is normalized into ProviderUsage windows per model_remains entry, surfacing
the interval and weekly limits with their reset times and a danger tone when
the server reports status=2.

* feat(app): add MiniMax brand icon for usage page

The quota panel resolves the icon via resolveProviderIconName, which falls
back to a generic Bot for any provider not in BUILTIN_PROVIDER_ICON_NAMES.
Register 'minimax' as a built-in icon and vendor the official 24×24 brand
mark (single Path, currentColor) as MiniMaxIcon so the usage card stops
showing the generic robot.

* refactor(server): flatten nested ternaries in MiniMax quota fetcher

Greptile review on #1662 called out two nested ternaries in toIntervalWindow
and toWeeklyWindow. Extract a toneForStatus helper that uses an explicit
if/else chain so the same status-to-tone mapping is shared between the
interval and weekly windows, and add the missing trailing newline.

* fix: format

packages/protocol/src/provider-icon-names.ts

@@ -3,6 +3,7 @@ export const BUILTIN_PROVIDER_ICON_NAMES = [
   "codex",
   "copilot",
   "kiro",
+  "minimax",
   "omp",
   "opencode",
   "pi",