fix: report names a RetroPie sentence gains

flycast now reads naomi2.zip, which the RetroArch list RetroPie inherits
already declares. The render added it to the flycast help sentences but
landed_changes counted additions only for entries the platform layer
lacks, so the report missed a name the diff carries. names_anew lets an
exporter whose unit is not the entry say so.

scripts/exporter/base_exporter.py

@@ -155,6 +155,13 @@ class BaseExporter(ABC):
         the render learned from the platform's own file."""
         return self.writable(fe)
 
+    def names_anew(self, fe: NativeFile) -> bool:
+        """Whether the render wrote, for the first time, a file the platform
+        layer already declares. Only a format whose unit is not the entry
+        does: a RetroPie help sentence can lack a name the inherited RetroArch
+        list carries."""
+        return False
+
     @classmethod
     def writable(cls, fe: NativeFile, require: str = "") -> bool:
         """Whether this format can carry the entry.

scripts/exporter/retropie_exporter.py

@@ -400,6 +400,11 @@ class Exporter(BaseExporter):
             return self.writable(fe)
         return id(fe) in getattr(self, "_named", set())
 
+    def names_anew(self, fe: NativeFile) -> bool:
+        """flycast's naomi2.zip is in the RetroArch list RetroPie inherits,
+        yet no flycast help sentence named it: the render adds it there."""
+        return fe.platform is not None and id(fe) in getattr(self, "_named", set())
+
     def outcome(
         self,
         systems: dict[str, NativeSystem],