Add Go-based PokeAPI fetch tool

Replaces the Python fetch_pokeapi.py script with a Go tool that crawls
a local PokeAPI instance and writes seed JSON files. Supports caching
and special encounter definitions via JSON config.

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

tools/fetch-pokeapi/models.go

@@ -0,0 +1,46 @@
+package main
+
+// Output JSON structs — identical schema to current Python output.
+
+type GameOutput struct {
+	Name        string  `json:"name"`
+	Slug        string  `json:"slug"`
+	Generation  int     `json:"generation"`
+	Region      string  `json:"region"`
+	ReleaseYear int     `json:"release_year"`
+	Color       *string `json:"color"`
+}
+
+type PokemonOutput struct {
+	PokeAPIID   int      `json:"pokeapi_id"`
+	NationalDex int      `json:"national_dex"`
+	Name        string   `json:"name"`
+	Types       []string `json:"types"`
+	SpriteURL   string   `json:"sprite_url"`
+}
+
+type EvolutionOutput struct {
+	FromPokeAPIID int     `json:"from_pokeapi_id"`
+	ToPokeAPIID   int     `json:"to_pokeapi_id"`
+	Trigger       string  `json:"trigger"`
+	MinLevel      *int    `json:"min_level"`
+	Item          *string `json:"item"`
+	HeldItem      *string `json:"held_item"`
+	Condition     *string `json:"condition"`
+}
+
+type RouteOutput struct {
+	Name       string            `json:"name"`
+	Order      int               `json:"order"`
+	Encounters []EncounterOutput `json:"encounters"`
+	Children   []RouteOutput     `json:"children,omitempty"`
+}
+
+type EncounterOutput struct {
+	PokeAPIID     int    `json:"pokeapi_id"`
+	PokemonName   string `json:"pokemon_name"`
+	Method        string `json:"method"`
+	EncounterRate int    `json:"encounter_rate"`
+	MinLevel      int    `json:"min_level"`
+	MaxLevel      int    `json:"max_level"`
+}