feat: add Console.readLine and Console.readInt, guessing game project

Add readLine and readInt operations to the Console effect for interactive
input. Create a number guessing game project demonstrating ADTs, pattern
matching, effects, and game state management.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/types.rs

@@ -780,6 +780,16 @@ impl TypeEnv {
                         params: Vec::new(),
                         return_type: Type::String,
                     },
+                    EffectOpDef {
+                        name: "readLine".to_string(),
+                        params: Vec::new(),
+                        return_type: Type::String,
+                    },
+                    EffectOpDef {
+                        name: "readInt".to_string(),
+                        params: Vec::new(),
+                        return_type: Type::Int,
+                    },
                 ],
             },
         );