Add comprehensive godoc documentation to all exported symbols

- Document all exported types, functions, methods, and constants across 52 files
- Add package-level doc comments to client, models, utils, and ynison packages
- Document HTTP method and endpoint path for each API client method
- Document model struct fields and DeJSON/DeList/ToJSON/ToMap methods
- Fix duplicate package doc comment in internal/models/base.go

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

internal/models/base.go

@@ -8,35 +8,38 @@ import (
 	"gitea.mrixs.me/Mrixs/yandex-music-api-go/internal/utils"
 )
 
-// Model is the base interface for all models
+// Model is the base interface for all models.
+// All model types implement this interface for JSON deserialization and serialization.
 type Model interface {
-	// DeJSON deserializes from JSON
+	// DeJSON deserializes a model from JSON data.
 	DeJSON(data []byte, c ClientInterface) (Model, error)
-	// DeList deserializes a list of models
+	// DeList deserializes a list of models from JSON data.
 	DeList(data []byte, c ClientInterface) ([]Model, error)
-	// ToJSON serializes to JSON
+	// ToJSON serializes the model to JSON.
 	ToJSON() ([]byte, error)
-	// ToMap converts to map
+	// ToMap converts the model to a map.
 	ToMap() (map[string]any, error)
 }
 
-// BaseModel provides common functionality for models
+// BaseModel provides common functionality for models, including a client reference.
 type BaseModel struct {
 	Client ClientInterface `json:"-"`
 }
 
-// NewBaseModel creates a new BaseModel
+// NewBaseModel creates a new BaseModel with the given client interface.
 func NewBaseModel(c ClientInterface) *BaseModel {
 	return &BaseModel{Client: c}
 }
 
-// DeJSON implements Model.DeJSON for basic models
+// DeJSON implements Model.DeJSON for basic models.
+// This should be overridden by concrete types.
 func (b *BaseModel) DeJSON(data []byte, c ClientInterface) (Model, error) {
 	// This should be overridden by concrete types
 	return nil, nil
 }
 
-// DeList implements Model.DeList for basic models
+// DeList implements Model.DeList for basic models.
+// This should be overridden by concrete types.
 func (b *BaseModel) DeList(data []byte, c ClientInterface) ([]Model, error) {
 	var rawList []json.RawMessage
 	if err := json.Unmarshal(data, &rawList); err != nil {
@@ -51,12 +54,12 @@ func (b *BaseModel) DeList(data []byte, c ClientInterface) ([]Model, error) {
 	return result, nil
 }
 
-// ToJSON serializes the model to JSON
+// ToJSON serializes the model to JSON using the default JSON backend.
 func (b *BaseModel) ToJSON() ([]byte, error) {
 	return utils.Marshal(b)
 }
 
-// ToMap converts the model to a map
+// ToMap converts the model to a map by serializing to JSON and unmarshaling into a map.
 func (b *BaseModel) ToMap() (map[string]any, error) {
 	data, err := b.ToJSON()
 	if err != nil {
@@ -69,12 +72,12 @@ func (b *BaseModel) ToMap() (map[string]any, error) {
 	return result, nil
 }
 
-// SetClient sets the client on the model
+// SetClient sets the client interface on the model.
 func (b *BaseModel) SetClient(c ClientInterface) {
 	b.Client = c
 }
 
-// GetClient returns the client
+// GetClient returns the client interface associated with the model.
 func (b *BaseModel) GetClient() ClientInterface {
 	return b.Client
 }