feat: Go backend, enhanced search, new widgets, Docker deploy

Major changes:
- Add Go backend (backend/) with microservices architecture
- Enhanced master-agents-svc: reranker, content-classifier, stealth-crawler,
  proxy-manager, media-search, fastClassifier, language detection
- New web-svc widgets: KnowledgeCard, ProductCard, ProfileCard, VideoCard,
  UnifiedCard, CardGallery, InlineImageGallery, SourcesPanel, RelatedQuestions
- Improved discover-svc with discover-db integration
- Docker deployment improvements (Caddyfile, vendor.sh, BUILD.md)
- Library-svc: project_id schema migration
- Remove deprecated finance-svc and travel-svc
- Localization improvements across services

Made-with: Cursor

backend/internal/llm/anthropic.go

@@ -0,0 +1,182 @@
+package llm
+
+import (
+	"bufio"
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+)
+
+type AnthropicClient struct {
+	baseClient
+	apiKey  string
+	baseURL string
+	client  *http.Client
+}
+
+func NewAnthropicClient(cfg ProviderConfig) (*AnthropicClient, error) {
+	baseURL := cfg.BaseURL
+	if baseURL == "" {
+		baseURL = "https://api.anthropic.com"
+	}
+
+	return &AnthropicClient{
+		baseClient: baseClient{
+			providerID: cfg.ProviderID,
+			modelKey:   cfg.ModelKey,
+		},
+		apiKey:  cfg.APIKey,
+		baseURL: strings.TrimSuffix(baseURL, "/"),
+		client:  &http.Client{},
+	}, nil
+}
+
+type anthropicRequest struct {
+	Model     string             `json:"model"`
+	Messages  []anthropicMessage `json:"messages"`
+	System    string             `json:"system,omitempty"`
+	MaxTokens int                `json:"max_tokens"`
+	Stream    bool               `json:"stream"`
+	Tools     []anthropicTool    `json:"tools,omitempty"`
+}
+
+type anthropicMessage struct {
+	Role    string `json:"role"`
+	Content string `json:"content"`
+}
+
+type anthropicTool struct {
+	Name        string      `json:"name"`
+	Description string      `json:"description"`
+	InputSchema interface{} `json:"input_schema"`
+}
+
+type anthropicStreamEvent struct {
+	Type  string `json:"type"`
+	Index int    `json:"index,omitempty"`
+	Delta struct {
+		Type string `json:"type,omitempty"`
+		Text string `json:"text,omitempty"`
+	} `json:"delta,omitempty"`
+	ContentBlock struct {
+		Type string `json:"type"`
+		Text string `json:"text,omitempty"`
+	} `json:"content_block,omitempty"`
+}
+
+func (c *AnthropicClient) StreamText(ctx context.Context, req StreamRequest) (<-chan StreamChunk, error) {
+	var systemPrompt string
+	messages := make([]anthropicMessage, 0)
+
+	for _, m := range req.Messages {
+		if m.Role == RoleSystem {
+			systemPrompt = m.Content
+			continue
+		}
+		role := string(m.Role)
+		if role == "tool" {
+			role = "user"
+		}
+		messages = append(messages, anthropicMessage{
+			Role:    role,
+			Content: m.Content,
+		})
+	}
+
+	maxTokens := req.Options.MaxTokens
+	if maxTokens == 0 {
+		maxTokens = 4096
+	}
+
+	anthropicReq := anthropicRequest{
+		Model:     c.modelKey,
+		Messages:  messages,
+		System:    systemPrompt,
+		MaxTokens: maxTokens,
+		Stream:    true,
+	}
+
+	if len(req.Tools) > 0 {
+		anthropicReq.Tools = make([]anthropicTool, len(req.Tools))
+		for i, t := range req.Tools {
+			anthropicReq.Tools[i] = anthropicTool{
+				Name:        t.Name,
+				Description: t.Description,
+				InputSchema: t.Schema,
+			}
+		}
+	}
+
+	body, err := json.Marshal(anthropicReq)
+	if err != nil {
+		return nil, err
+	}
+
+	httpReq, err := http.NewRequestWithContext(ctx, "POST", c.baseURL+"/v1/messages", bytes.NewReader(body))
+	if err != nil {
+		return nil, err
+	}
+
+	httpReq.Header.Set("Content-Type", "application/json")
+	httpReq.Header.Set("x-api-key", c.apiKey)
+	httpReq.Header.Set("anthropic-version", "2023-06-01")
+
+	resp, err := c.client.Do(httpReq)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(resp.Body)
+		resp.Body.Close()
+		return nil, fmt.Errorf("anthropic API error: %d - %s", resp.StatusCode, string(body))
+	}
+
+	ch := make(chan StreamChunk, 100)
+	go func() {
+		defer close(ch)
+		defer resp.Body.Close()
+
+		scanner := bufio.NewScanner(resp.Body)
+		for scanner.Scan() {
+			line := scanner.Text()
+			if !strings.HasPrefix(line, "data: ") {
+				continue
+			}
+
+			data := strings.TrimPrefix(line, "data: ")
+			if data == "[DONE]" {
+				return
+			}
+
+			var event anthropicStreamEvent
+			if err := json.Unmarshal([]byte(data), &event); err != nil {
+				continue
+			}
+
+			switch event.Type {
+			case "content_block_delta":
+				if event.Delta.Text != "" {
+					ch <- StreamChunk{ContentChunk: event.Delta.Text}
+				}
+			case "message_stop":
+				ch <- StreamChunk{FinishReason: "stop"}
+				return
+			}
+		}
+	}()
+
+	return ch, nil
+}
+
+func (c *AnthropicClient) GenerateText(ctx context.Context, req StreamRequest) (string, error) {
+	ch, err := c.StreamText(ctx, req)
+	if err != nil {
+		return "", err
+	}
+	return readAllChunks(ch), nil
+}