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/feed.go

@@ -1,10 +1,11 @@
+// Package models provides data models for the Yandex Music API.
 package models
 
 import (
 	"encoding/json"
 )
 
-// Feed represents the main feed
+// Feed represents the main feed from the Yandex Music API.
 type Feed struct {
 	BaseModel
 	Days               []Day               `json:"days"`
@@ -12,7 +13,7 @@ type Feed struct {
 	PlayContexts       []PlayContext       `json:"play_contexts"`
 }
 
-// DeJSON deserializes a Feed from JSON
+// DeJSON deserializes a Feed from JSON data.
 func (f *Feed) DeJSON(data []byte, c ClientInterface) (Model, error) {
 	var raw map[string]json.RawMessage
 	if err := json.Unmarshal(data, &raw); err != nil {
@@ -40,7 +41,7 @@ func (f *Feed) DeJSON(data []byte, c ClientInterface) (Model, error) {
 	return feed, nil
 }
 
-// DeList deserializes a list of Feeds
+// DeList deserializes a list of Feeds from JSON data.
 func (f *Feed) DeList(data []byte, c ClientInterface) ([]Model, error) {
 	var rawList []json.RawMessage
 	if err := json.Unmarshal(data, &rawList); err != nil {
@@ -58,7 +59,7 @@ func (f *Feed) DeList(data []byte, c ClientInterface) ([]Model, error) {
 	return result, nil
 }
 
-// Day represents a day in the feed
+// Day represents a day in the feed.
 type Day struct {
 	BaseModel
 	Date               string              `json:"date"`
@@ -68,7 +69,7 @@ type Day struct {
 	GeneratedPlaylists []GeneratedPlaylist `json:"generated_playlists"`
 }
 
-// DeJSON deserializes a Day from JSON
+// DeJSON deserializes a Day from JSON data.
 func (d *Day) DeJSON(data []byte, c ClientInterface) (Model, error) {
 	var raw map[string]json.RawMessage
 	if err := json.Unmarshal(data, &raw); err != nil {
@@ -100,7 +101,7 @@ func (d *Day) DeJSON(data []byte, c ClientInterface) (Model, error) {
 	return day, nil
 }
 
-// DeList deserializes a list of Days
+// DeList deserializes a list of Days from JSON data.
 func (d *Day) DeList(data []byte, c ClientInterface) ([]Model, error) {
 	var rawList []json.RawMessage
 	if err := json.Unmarshal(data, &rawList); err != nil {
@@ -118,7 +119,7 @@ func (d *Day) DeList(data []byte, c ClientInterface) ([]Model, error) {
 	return result, nil
 }
 
-// DayBlock represents a block in a day
+// DayBlock represents a block in a day.
 type DayBlock struct {
 	BaseModel
 	ID          string        `json:"id"`
@@ -128,7 +129,7 @@ type DayBlock struct {
 	Data        *DayBlockData `json:"data"`
 }
 
-// DayBlockData represents data in a day block
+// DayBlockData represents data in a day block.
 type DayBlockData struct {
 	Tracks            []Track            `json:"tracks"`
 	Playlists         []Playlist         `json:"playlists"`
@@ -137,7 +138,7 @@ type DayBlockData struct {
 	GeneratedPlaylist *GeneratedPlaylist `json:"generated_playlist"`
 }
 
-// GeneratedPlaylist represents a generated playlist
+// GeneratedPlaylist represents a generated playlist.
 type GeneratedPlaylist struct {
 	BaseModel
 	ID          string  `json:"id"`
@@ -153,7 +154,7 @@ type GeneratedPlaylist struct {
 	Tracks      []Track `json:"tracks"`
 }
 
-// DeJSON deserializes a GeneratedPlaylist from JSON
+// DeJSON deserializes a GeneratedPlaylist from JSON data.
 func (gp *GeneratedPlaylist) DeJSON(data []byte, c ClientInterface) (Model, error) {
 	var raw map[string]json.RawMessage
 	if err := json.Unmarshal(data, &raw); err != nil {
@@ -201,7 +202,7 @@ func (gp *GeneratedPlaylist) DeJSON(data []byte, c ClientInterface) (Model, erro
 	return playlist, nil
 }
 
-// DeList deserializes a list of GeneratedPlaylists
+// DeList deserializes a list of GeneratedPlaylists from JSON data.
 func (gp *GeneratedPlaylist) DeList(data []byte, c ClientInterface) ([]Model, error) {
 	var rawList []json.RawMessage
 	if err := json.Unmarshal(data, &rawList); err != nil {
@@ -219,7 +220,7 @@ func (gp *GeneratedPlaylist) DeList(data []byte, c ClientInterface) ([]Model, er
 	return result, nil
 }
 
-// Event represents a feed event
+// Event represents a feed event.
 type Event struct {
 	BaseModel
 	Timestamp  string `json:"timestamp"`
@@ -231,7 +232,7 @@ type Event struct {
 	Action     string `json:"action"`
 }
 
-// AlbumEvent represents an album event
+// AlbumEvent represents an album event.
 type AlbumEvent struct {
 	BaseModel
 	Album     *Album `json:"album"`
@@ -240,7 +241,7 @@ type AlbumEvent struct {
 	Action    string `json:"action"`
 }
 
-// ArtistEvent represents an artist event
+// ArtistEvent represents an artist event.
 type ArtistEvent struct {
 	BaseModel
 	Artist    *Artist `json:"artist"`
@@ -249,7 +250,7 @@ type ArtistEvent struct {
 	Action    string  `json:"action"`
 }
 
-// TrackWithAds represents a track with ads
+// TrackWithAds represents a track with ads.
 type TrackWithAds struct {
 	BaseModel
 	Track    *Track    `json:"track"`
@@ -257,7 +258,7 @@ type TrackWithAds struct {
 	AdParams *AdParams `json:"ad_params"`
 }
 
-// Ad represents an ad
+// Ad represents an ad.
 type Ad struct {
 	BaseModel
 	ID          string `json:"id"`
@@ -269,7 +270,7 @@ type Ad struct {
 	Duration    int    `json:"duration"`
 }
 
-// AdParams represents ad parameters
+// AdParams represents ad parameters.
 type AdParams struct {
 	BaseModel
 	Frequency int    `json:"frequency"`