[api] Use RAW_ENCODE_SMALL_MAP for max_value encode optimization

Replace inline encode_func check with a lookup table, matching the
existing RAW_ENCODE_MAP pattern.

script/api_protobuf/api_protobuf.py

@@ -240,6 +240,12 @@ class TypeInfo(ABC):
         "encode_bool": "buffer.write_raw_byte({value} ? 0x01 : 0x00);",
     }
 
+    # When max_value < 128, the varint is always 1 byte — use a direct byte write
+    RAW_ENCODE_SMALL_MAP: dict[str, str] = {
+        "encode_uint32": "buffer.write_raw_byte(static_cast<uint8_t>({value}));",
+        "encode_uint64": "buffer.write_raw_byte(static_cast<uint8_t>({value}));",
+    }
+
     def _encode_with_precomputed_tag(self, value_expr: str) -> str | None:
         """Try to emit a precomputed-tag encode for a forced field.
 
@@ -252,22 +258,12 @@ class TypeInfo(ABC):
         tag = self.calculate_tag()
         if tag >= 128:
             return None
-        # When max_value < 128, varint is always 1 byte - use direct byte write
         max_val = self.max_value
-        if (
-            max_val is not None
-            and max_val < 128
-            and self.encode_func
-            in (
-                "encode_uint32",
-                "encode_uint64",
-            )
-        ):
-            return (
-                f"buffer.write_raw_byte({tag});\n"
-                f"buffer.write_raw_byte(static_cast<uint8_t>({value_expr}));"
-            )
-        raw_expr = self.RAW_ENCODE_MAP.get(self.encode_func)
+        raw_expr = (
+            self.RAW_ENCODE_SMALL_MAP.get(self.encode_func)
+            if max_val is not None and max_val < 128
+            else self.RAW_ENCODE_MAP.get(self.encode_func)
+        )
         if raw_expr is None:
             return None
         return f"buffer.write_raw_byte({tag});\n{raw_expr.format(value=value_expr)}"