fix(gui): proper splitter placement for persona and bias panels

- Persona editor: splitter shown when BOTH models and prompt open (not just prompt)
- Bias profiles: move splitter OUTSIDE btool_scroll child, between both sections
- Fixed nesting issues causing EndTable/EndChild errors

config.toml

@@ -1,6 +1,6 @@
 [ai]
 provider = "minimax"
-model = "MiniMax-M2.5"
+model = "MiniMax-M2.7"
 temperature = 0.0
 top_p = 1.0
 max_tokens = 32000