onboard(minimax): flatten auth to 4 direct choices, unify CN/Global under single provider (#44284)

Replace the multi-step MiniMax onboarding wizard with 4 flat options:
- MiniMax Global — OAuth (minimax.io)
- MiniMax Global — API Key (minimax.io)
- MiniMax CN — OAuth (minimaxi.com)
- MiniMax CN — API Key (minimaxi.com)

Storage changes:
- Unify CN and Global under provider "minimax" (baseUrl distinguishes region)
- Profiles: minimax:global / minimax:cn (both regions can coexist)
- Model ref: minimax/MiniMax-M2.5 (no more minimax-cn/ prefix)
- Remove LM Studio local mode and Lightning/Highspeed choice

Backward compatibility:
- Keep minimax-cn in provider-env-vars for existing configs
- Accept minimax-cn as legacy tokenProvider in CI pipelines
- Error with migration hint for removed auth choices in non-interactive mode
- Warn when dual-profile overwrites shared provider baseUrl

Made-with: Cursor

docs/providers/minimax.md

@@ -151,7 +151,7 @@ Configure manually via `openclaw.json`:
           {
             id: "minimax-m2.5-gs32",
             name: "MiniMax M2.5 GS32",
-            reasoning: false,
+            reasoning: true,
             input: ["text"],
             cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
             contextWindow: 196608,