Add seed JSON output (per-game, games.json, pokemon.json)

Wire output module into CLI pipeline: route ordering, special encounter
merging, and JSON writing for per-game encounters, global games list,
and pokemon list with types and sprite paths.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tools/import-pokedb/import_pokedb/mappings.py

@@ -464,6 +464,16 @@ class PokemonMapper:
 
         return None
 
+    def lookup_by_id(self, pokeapi_id: int) -> tuple[int, str] | None:
+        """Look up a pokemon by its pokeapi_id.
+
+        Returns (pokeapi_id, display_name) or None if not found.
+        """
+        if pokeapi_id in self._id_to_info:
+            _, name = self._id_to_info[pokeapi_id]
+            return (pokeapi_id, name)
+        return None
+
     def get_sprite_url(self, pokemon_form_identifier: str | None) -> str | None:
         """Get the PokeDB CDN sprite URL (100x100 medium) for a form identifier."""
         if not pokemon_form_identifier: