Configurable thinking budget (default to medium) (#494)

src/lib/schemas.ts

@@ -142,6 +142,7 @@ export const UserSettingsSchema = z.object({
   experiments: ExperimentsSchema.optional(),
   lastShownReleaseNotesVersion: z.string().optional(),
   maxChatTurnsInContext: z.number().optional(),
+  thinkingBudget: z.enum(["low", "medium", "high"]).optional(),
   enableProLazyEditsMode: z.boolean().optional(),
   enableProSmartFilesContextMode: z.boolean().optional(),
   selectedTemplateId: z.string().optional(),