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/music_history.go

@@ -1,10 +1,11 @@
+// Package models provides data models for the Yandex Music API.
 package models
 
 import (
 	"encoding/json"
 )
 
-// MusicHistory represents music history
+// MusicHistory represents music history from the Yandex Music API.
 type MusicHistory struct {
 	BaseModel
 	Tabs    []MusicHistoryTab             `json:"tabs"`
@@ -13,7 +14,7 @@ type MusicHistory struct {
 	Context *MusicHistoryContextFullModel `json:"context"`
 }
 
-// DeJSON deserializes a MusicHistory from JSON
+// DeJSON deserializes a MusicHistory from JSON data.
 func (mh *MusicHistory) DeJSON(data []byte, client ClientInterface) (Model, error) {
 	var raw map[string]json.RawMessage
 	if err := json.Unmarshal(data, &raw); err != nil {
@@ -46,7 +47,7 @@ func (mh *MusicHistory) DeJSON(data []byte, client ClientInterface) (Model, erro
 	return history, nil
 }
 
-// DeList deserializes a list of MusicHistory
+// DeList deserializes a list of MusicHistory from JSON data.
 func (mh *MusicHistory) DeList(data []byte, client ClientInterface) ([]Model, error) {
 	var rawList []json.RawMessage
 	if err := json.Unmarshal(data, &rawList); err != nil {
@@ -64,7 +65,7 @@ func (mh *MusicHistory) DeList(data []byte, client ClientInterface) ([]Model, er
 	return result, nil
 }
 
-// MusicHistoryTab represents a music history tab
+// MusicHistoryTab represents a music history tab.
 type MusicHistoryTab struct {
 	BaseModel
 	ID          string `json:"id"`
@@ -75,7 +76,7 @@ type MusicHistoryTab struct {
 	Position    int    `json:"position"`
 }
 
-// MusicHistoryGroup represents a music history group
+// MusicHistoryGroup represents a music history group.
 type MusicHistoryGroup struct {
 	BaseModel
 	ID          string             `json:"id"`
@@ -85,7 +86,7 @@ type MusicHistoryGroup struct {
 	Total       int                `json:"total"`
 }
 
-// MusicHistoryItem represents a music history item
+// MusicHistoryItem represents a music history item.
 type MusicHistoryItem struct {
 	BaseModel
 	ID        string                `json:"id"`
@@ -100,7 +101,7 @@ type MusicHistoryItem struct {
 	Context   *MusicHistoryItemData `json:"context"`
 }
 
-// MusicHistoryItemData represents music history item data
+// MusicHistoryItemData represents music history item data.
 type MusicHistoryItemData struct {
 	BaseModel
 	Source      string       `json:"source"`
@@ -112,14 +113,14 @@ type MusicHistoryItemData struct {
 	Progress    float64      `json:"progress"`
 }
 
-// MusicHistoryItemID represents music history item ID
+// MusicHistoryItemID represents music history item ID.
 type MusicHistoryItemID struct {
 	BaseModel
 	ID   string `json:"id"`
 	Type string `json:"type"`
 }
 
-// MusicHistoryItems represents music history items
+// MusicHistoryItems represents music history items.
 type MusicHistoryItems struct {
 	BaseModel
 	Items    []MusicHistoryItem `json:"items"`
@@ -128,7 +129,7 @@ type MusicHistoryItems struct {
 	PageSize int                `json:"page_size"`
 }
 
-// MusicHistoryContextFullModel represents music history context full model
+// MusicHistoryContextFullModel represents music history context full model.
 type MusicHistoryContextFullModel struct {
 	BaseModel
 	DeviceID   string `json:"device_id"`