feat(pi): add 'max' thinking level support (#2267)

* feat(pi): add 'max' thinking level support

Pi recently introduced a new 'max' thinking level beyond 'xhigh'.
This adds it to the type union, the UI options array, and the
runtime type guard so Paseo users can select it.

Changes:
- rpc-types.ts: add 'max' to PiThinkingLevel union
- agent.ts: add max entry to PI_THINKING_OPTIONS
- agent.ts: add 'max' to isPiThinkingLevel guard

* fix(pi): clarify xhigh description after adding max level

xhigh's 'Maximum reasoning' is now misleading since max is the true
maximum. Changed to 'Very deep reasoning' per review feedback.

packages/server/src/server/agent/providers/pi/agent.ts

@@ -173,7 +173,8 @@ const PI_THINKING_OPTIONS: ReadonlyArray<{
   { id: "low", label: "Low", description: "Faster reasoning" },
   { id: "medium", label: "Medium", description: "Balanced reasoning", isDefault: true },
   { id: "high", label: "High", description: "Deeper reasoning" },
-  { id: "xhigh", label: "XHigh", description: "Maximum reasoning" },
+  { id: "xhigh", label: "XHigh", description: "Very deep reasoning" },
+  { id: "max", label: "Max", description: "Extreme reasoning" },
 ] as const;
 
 export interface PiRpcAgentClientOptions {
@@ -329,7 +330,8 @@ function isPiThinkingLevel(value: string | null | undefined): value is PiThinkin
     value === "low" ||
     value === "medium" ||
     value === "high" ||
-    value === "xhigh"
+    value === "xhigh" ||
+    value === "max"
   );
 }
 

packages/server/src/server/agent/providers/pi/rpc-types.ts

@@ -1,4 +1,4 @@
-export type PiThinkingLevel = "off" | "minimal" | "low" | "medium" | "high" | "xhigh";
+export type PiThinkingLevel = "off" | "minimal" | "low" | "medium" | "high" | "xhigh" | "max";
 
 export interface PiImageContent {
   type: "image";