feat(recipe): add fields for generic file discovery

Introduce ProjectLanguages and Extensions fields to the Recipe struct
to support option 2 for generic file discovery. Also update comments
for internal fields populated by the loader.

internal/recipe/types.go

@@ -6,7 +6,13 @@ type Recipe struct {
 	Version              string               `yaml:"version"`
 	Parameters           map[string]Parameter `yaml:"parameters"`
 	AllowedShellCommands []string             `yaml:"allowed_shell_commands"`
-	Overview             string               `yaml:"-"` // extracted from markdown
+
+	// New fields for generic file discovery (option 2)
+	ProjectLanguages []string            `yaml:"project_languages"`
+	Extensions       map[string][]string `yaml:"extensions"`
+
+	// Internal fields populated by loader
+	Overview           string `yaml:"-"`
 	Steps              []Step `yaml:"-"`
 	FinalSummaryPrompt string `yaml:"-"`
 }