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/client/settings.go

@@ -1,3 +1,4 @@
+// Package client provides methods for interacting with Yandex Music API endpoints.
 package client
 
 import (
@@ -6,7 +7,7 @@ import (
 	"gitea.mrixs.me/Mrixs/yandex-music-api-go/internal/models"
 )
 
-// GetSettings gets user settings
+// GetSettings gets user settings (GET /account/settings).
 func (c *Client) GetSettings(ctx context.Context) (*models.AccountSettings, error) {
 	var result models.AccountSettings
 	if err := c.request.Get(ctx, "/account/settings", nil, &result); err != nil {
@@ -15,7 +16,7 @@ func (c *Client) GetSettings(ctx context.Context) (*models.AccountSettings, erro
 	return &result, nil
 }
 
-// UpdateSettings updates user settings
+// UpdateSettings updates user settings (PUT /account/settings).
 func (c *Client) UpdateSettings(ctx context.Context, settings *models.AccountSettings) (*models.AccountSettings, error) {
 	var result models.AccountSettings
 	if err := c.request.Put(ctx, "/account/settings", settings, &result); err != nil {
@@ -24,7 +25,7 @@ func (c *Client) UpdateSettings(ctx context.Context, settings *models.AccountSet
 	return &result, nil
 }
 
-// GetExperiments gets experiments
+// GetExperiments gets experiments (GET /experiments).
 func (c *Client) GetExperiments(ctx context.Context) (*models.Experiments, error) {
 	var result models.Experiments
 	if err := c.request.Get(ctx, "/experiments", nil, &result); err != nil {
@@ -33,7 +34,7 @@ func (c *Client) GetExperiments(ctx context.Context) (*models.Experiments, error
 	return &result, nil
 }
 
-// GetExperimentDetails gets experiment details
+// GetExperimentDetails gets experiment details for the given experiment ID (GET /experiments/details).
 func (c *Client) GetExperimentDetails(ctx context.Context, experimentID string) (*models.ExperimentDetail, error) {
 	params := map[string]string{
 		"experiment_id": experimentID,
@@ -45,7 +46,7 @@ func (c *Client) GetExperimentDetails(ctx context.Context, experimentID string)
 	return &result, nil
 }
 
-// GetPermissions gets user permissions
+// GetPermissions gets user permissions (GET /permissions).
 func (c *Client) GetPermissions(ctx context.Context) (*models.Permissions, error) {
 	var result models.Permissions
 	if err := c.request.Get(ctx, "/permissions", nil, &result); err != nil {
@@ -54,7 +55,7 @@ func (c *Client) GetPermissions(ctx context.Context) (*models.Permissions, error
 	return &result, nil
 }
 
-// GetPermissionAlerts gets permission alerts
+// GetPermissionAlerts gets permission alerts (GET /permission-alerts).
 func (c *Client) GetPermissionAlerts(ctx context.Context) (*models.PermissionAlerts, error) {
 	var result models.PermissionAlerts
 	if err := c.request.Get(ctx, "/permission-alerts", nil, &result); err != nil {
@@ -63,7 +64,7 @@ func (c *Client) GetPermissionAlerts(ctx context.Context) (*models.PermissionAle
 	return &result, nil
 }
 
-// GetContentRestrictions gets content restrictions
+// GetContentRestrictions gets content restrictions (GET /content-restrictions).
 func (c *Client) GetContentRestrictions(ctx context.Context) (*models.ContentRestrictions, error) {
 	var result models.ContentRestrictions
 	if err := c.request.Get(ctx, "/content-restrictions", nil, &result); err != nil {