feat: enhance feed detail functionality with MCP interface improvements (#45)

* feat: add feed detail page functionality with gin and MCP interfaces

Add comprehensive Feed detail page support:
- Create new FeedDetailAction in xiaohongshu/feed_detail.go
- Add HTTP API endpoint POST /api/v1/feeds/detail
- Add MCP tool 'get_feed_detail' for MCP protocol support
- Support feed_id and xsec_token parameters (both required)
- Raw __INITIAL_STATE__ JSON data saved to feed_detail.json
- Return structured data for both HTTP and MCP interfaces

🤖 Generated with [Claude Code](https://claude.ai/code)

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

* feat: enhance feed detail functionality with MCP interface improvements

- Add comprehensive feed detail page support with proper data extraction
- Create dedicated feed_detail.go file for FeedDetailAction
- Optimize Go struct definitions based on actual JSON data analysis
- Remove unnecessary fields from FeedDetail, DetailImageInfo, CommentList, and Comment structs
- Update MCP interface description to reflect comment retrieval capability
- Support both HTTP REST API and MCP protocol interfaces
- Implement proper Vue 3 reactive data extraction from window.__INITIAL_STATE__
- Include feed content, user info, interaction data, and comment lists

🤖 Generated with [Claude Code](https://claude.ai/code)

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

* fix: restore JSON file writing for testing and improve code structure

- Restore feed_detail.json file writing for testing purposes
- Improve error handling by separating marshal and unmarshal steps
- Keep the original data extraction logic for complex Vue reactive data structure

🤖 Generated with [Claude Code](https://claude.ai/code)

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

* refactor: simplify JSON unmarshaling using struct instead of map[string]any

- Replace complex map[string]any extraction with direct struct unmarshaling
- Define inline struct matching the actual JSON response structure
- Remove unnecessary extractFeedDetailData and extractNestedValue methods
- Significantly reduce code complexity and improve readability

🤖 Generated with [Claude Code](https://claude.ai/code)

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

* docs: improve MCP interface descriptions for better usability

- Enhance get_feed_detail parameter descriptions with clear source information
- Clarify publish_content images parameter supports both local paths and URLs
- Improve search_feeds description to specify supported search types
- Keep descriptions concise and practical without over-complication

🤖 Generated with [Claude Code](https://claude.ai/code)

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

* fix: revert search_feeds keyword description to keep it simple

- Remove unnecessary details from keyword description
- Keep interface descriptions concise and clear

🤖 Generated with [Claude Code](https://claude.ai/code)

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

---------

Co-authored-by: Claude <noreply@anthropic.com>

xiaohongshu/feed_detail.go

@@ -0,0 +1,77 @@
+package xiaohongshu
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/go-rod/rod"
+)
+
+// FeedDetailAction 表示 Feed 详情页动作
+type FeedDetailAction struct {
+	page *rod.Page
+}
+
+// NewFeedDetailAction 创建 Feed 详情页动作
+func NewFeedDetailAction(page *rod.Page) *FeedDetailAction {
+	return &FeedDetailAction{page: page}
+}
+
+// GetFeedDetail 获取 Feed 详情页数据
+func (f *FeedDetailAction) GetFeedDetail(ctx context.Context, feedID, xsecToken string) (*FeedDetailResponse, error) {
+	page := f.page.Context(ctx).Timeout(60 * time.Second)
+
+	// 构建详情页 URL
+	url := fmt.Sprintf("https://www.xiaohongshu.com/explore/%s?xsec_token=%s&xsec_source=pc_feed", feedID, xsecToken)
+
+	// 导航到详情页
+	page.MustNavigate(url)
+	page.MustWaitStable()
+	page.MustWait(`() => window.__INITIAL_STATE__ !== undefined`)
+
+	// 获取 window.__INITIAL_STATE__ 并转换为 JSON 字符串
+	result := page.MustEval(`() => {
+		if (window.__INITIAL_STATE__) {
+			return JSON.stringify(window.__INITIAL_STATE__);
+		}
+		return "";
+	}`).String()
+
+	if result == "" {
+		return nil, fmt.Errorf("__INITIAL_STATE__ not found")
+	}
+
+	// 将原始结果保存到 feed_detail.json 文件用于测试
+	err := os.WriteFile("feed_detail.json", []byte(result), 0644)
+	if err != nil {
+		return nil, fmt.Errorf("failed to write feed_detail.json: %w", err)
+	}
+
+	// 定义响应结构并直接反序列化
+	var initialState struct {
+		Note struct {
+			NoteDetailMap map[string]struct {
+				Note     FeedDetail  `json:"note"`
+				Comments CommentList `json:"comments"`
+			} `json:"noteDetailMap"`
+		} `json:"note"`
+	}
+
+	if err := json.Unmarshal([]byte(result), &initialState); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal __INITIAL_STATE__: %w", err)
+	}
+
+	// 从 noteDetailMap 中获取对应 feedID 的数据
+	noteDetail, exists := initialState.Note.NoteDetailMap[feedID]
+	if !exists {
+		return nil, fmt.Errorf("feed %s not found in noteDetailMap", feedID)
+	}
+
+	return &FeedDetailResponse{
+		Note:     noteDetail.Note,
+		Comments: noteDetail.Comments,
+	}, nil
+}