feat(minimax): add MiniMax-M3, set as default, drop M2.5/M2.1/M2

- Add MINIMAX_M3 = "MiniMax-M3" constant and put it first in MODEL_LIST
- Default MinimaxBot model: MiniMax-M2.7 -> MiniMax-M3
- Keep MiniMax-M2.7 and MiniMax-M2.7-highspeed as legacy options
- Drop MINIMAX_M2_5 / MINIMAX_M2_1 / MINIMAX_M2_1_LIGHTNING / MINIMAX_M2
- Update web console recommended/provider model lists
- Update README capability table and docs/models index (en/zh/ja)
- Update docs/models/minimax.mdx and coding-plan.mdx MiniMax section
- Update run.sh / run.ps1 installer default and menu hint
- Update zh CLI status sample output
- Update unit tests to assert new M3 default and constant

TTS (speech-2.*) and API base URL remain unchanged.

models/minimax/minimax_bot.py

@@ -22,7 +22,7 @@ class MinimaxBot(Bot):
     def __init__(self):
         super().__init__()
         self.args = {
-            "model": conf().get("model") or "MiniMax-M2.7",
+            "model": conf().get("model") or "MiniMax-M3",
             "temperature": conf().get("temperature", 0.3),
             "top_p": conf().get("top_p", 0.95),
         }