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/client.go

@@ -0,0 +1,145 @@
+package llm
+
+import (
+	"context"
+	"fmt"
+	"io"
+)
+
+type Role string
+
+const (
+	RoleSystem    Role = "system"
+	RoleUser      Role = "user"
+	RoleAssistant Role = "assistant"
+	RoleTool      Role = "tool"
+)
+
+type Message struct {
+	Role       Role           `json:"role"`
+	Content    string         `json:"content"`
+	ToolCalls  []ToolCall     `json:"tool_calls,omitempty"`
+	ToolCallID string         `json:"tool_call_id,omitempty"`
+	Name       string         `json:"name,omitempty"`
+	Images     []ImageContent `json:"images,omitempty"`
+}
+
+type ImageContent struct {
+	Type     string `json:"type"`
+	URL      string `json:"url,omitempty"`
+	Data     string `json:"data,omitempty"`
+	IsBase64 bool   `json:"isBase64,omitempty"`
+}
+
+type ToolCall struct {
+	ID       string                 `json:"id"`
+	Name     string                 `json:"name"`
+	Arguments map[string]interface{} `json:"arguments"`
+}
+
+type Tool struct {
+	Name        string      `json:"name"`
+	Description string      `json:"description"`
+	Schema      interface{} `json:"schema"`
+}
+
+type StreamOptions struct {
+	MaxTokens   int     `json:"max_tokens,omitempty"`
+	Temperature float64 `json:"temperature,omitempty"`
+	TopP        float64 `json:"top_p,omitempty"`
+	StopWords   []string `json:"stop,omitempty"`
+}
+
+type StreamChunk struct {
+	ContentChunk  string     `json:"content_chunk,omitempty"`
+	ToolCallChunk []ToolCall `json:"tool_call_chunk,omitempty"`
+	FinishReason  string     `json:"finish_reason,omitempty"`
+}
+
+type StreamRequest struct {
+	Messages []Message     `json:"messages"`
+	Tools    []Tool        `json:"tools,omitempty"`
+	Options  StreamOptions `json:"options,omitempty"`
+}
+
+type Client interface {
+	StreamText(ctx context.Context, req StreamRequest) (<-chan StreamChunk, error)
+	GenerateText(ctx context.Context, req StreamRequest) (string, error)
+	GetProviderID() string
+	GetModelKey() string
+}
+
+type ProviderConfig struct {
+	ProviderID    string `json:"providerId"`
+	ModelKey      string `json:"key"`
+	APIKey        string `json:"apiKey,omitempty"`
+	BaseURL       string `json:"baseUrl,omitempty"`
+	AgentAccessID string `json:"agentAccessId,omitempty"`
+}
+
+func NewClient(cfg ProviderConfig) (Client, error) {
+	switch cfg.ProviderID {
+	case "timeweb":
+		return NewTimewebClient(TimewebConfig{
+			BaseURL:       cfg.BaseURL,
+			AgentAccessID: cfg.AgentAccessID,
+			APIKey:        cfg.APIKey,
+			ModelKey:      cfg.ModelKey,
+			ProxySource:   "gooseek",
+		})
+	case "openai":
+		return NewOpenAIClient(cfg)
+	case "anthropic":
+		return NewAnthropicClient(cfg)
+	case "gemini", "google":
+		return NewGeminiClient(cfg)
+	default:
+		return nil, fmt.Errorf("unknown provider: %s", cfg.ProviderID)
+	}
+}
+
+type baseClient struct {
+	providerID string
+	modelKey   string
+}
+
+func (c *baseClient) GetProviderID() string {
+	return c.providerID
+}
+
+func (c *baseClient) GetModelKey() string {
+	return c.modelKey
+}
+
+func readAllChunks(ch <-chan StreamChunk) string {
+	var result string
+	for chunk := range ch {
+		result += chunk.ContentChunk
+	}
+	return result
+}
+
+type streamReader struct {
+	ch     <-chan StreamChunk
+	buffer []byte
+}
+
+func (r *streamReader) Read(p []byte) (n int, err error) {
+	if len(r.buffer) > 0 {
+		n = copy(p, r.buffer)
+		r.buffer = r.buffer[n:]
+		return n, nil
+	}
+
+	chunk, ok := <-r.ch
+	if !ok {
+		return 0, io.EOF
+	}
+
+	data := []byte(chunk.ContentChunk)
+	n = copy(p, data)
+	if n < len(data) {
+		r.buffer = data[n:]
+	}
+	return n, nil
+}