feat(llm): add LLM call recording with admin panel integration

- llm.Adapter: SetCallLogger hook for recording every API call
- llm.CallLogger: ring-buffer with Recent+Stats for admin API
- main.go: wire DeepSeek adapter to CallLogger
- Fix: single CallLogger instance for both recording and display
- Metrics: model name, duration, success/fail, tokens
- All 16 packages pass

backend/services/ai-core/llm/llm.go

@@ -39,8 +39,9 @@ func DefaultConfig() Config {
 
 // Adapter handles communication with an OpenAI-compatible LLM API.
 type Adapter struct {
-	cfg    Config
-	client *http.Client
+	cfg      Config
+	client   *http.Client
+	onCall   func(call CallRecord) // Hook for logging each LLM call
 }
 
 // NewAdapter creates a new LLM adapter.
@@ -58,11 +59,29 @@ func NewAdapter(cfg Config) *Adapter {
 	}
 }
 
+// SetCallLogger injects a callback that is invoked after each LLM call.
+func (a *Adapter) SetCallLogger(fn func(call CallRecord)) {
+	a.onCall = fn
+}
+
+// CallRecord holds metadata about a single LLM API call.
+type CallRecord struct {
+	Time           time.Time
+	Model          string
+	Purpose        string
+	PromptTokens   int
+	CompletionTokens int
+	DurationMs     int64
+	Success        bool
+	Error          string
+}
+
 // ModelName returns the configured model name.
 func (a *Adapter) ModelName() string { return a.cfg.Model }
 
 // Chat sends a chat completion request and returns the full response.
 func (a *Adapter) Chat(ctx context.Context, messages []model.LLMMessage) (*model.LLMResponse, error) {
+	start := time.Now()
 	body := map[string]any{
 		"model":    a.cfg.Model,
 		"messages": messages,
@@ -73,27 +92,23 @@ func (a *Adapter) Chat(ctx context.Context, messages []model.LLMMessage) (*model
 		if choices, ok := data["choices"].([]any); ok && len(choices) > 0 {
 			choice := choices[0].(map[string]any)
 			if msg, ok := choice["message"].(map[string]any); ok {
-				if content, ok := msg["content"].(string); ok {
-					resp.Content = content
-				}
-			}
-			if reason, ok := choice["finish_reason"].(string); ok {
-				resp.FinishReason = reason
+				if content, ok := msg["content"].(string); ok { resp.Content = content }
 			}
+			if reason, ok := choice["finish_reason"].(string); ok { resp.FinishReason = reason }
 		}
 		if usage, ok := data["usage"].(map[string]any); ok {
-			if total, ok := usage["total_tokens"].(float64); ok {
-				resp.TokensUsed = int(total)
-			}
+			if total, ok := usage["total_tokens"].(float64); ok { resp.TokensUsed = int(total) }
 		}
 		return nil
 	})
 
+	a.recordCall(start, "chat", resp.TokensUsed, 0, err)
 	return resp, err
 }
 
-// ChatStream sends a chat completion request and returns a token channel for streaming.
+// ChatStream sends a chat completion request and returns a token channel.
 func (a *Adapter) ChatStream(ctx context.Context, messages []model.LLMMessage) (<-chan model.StreamToken, error) {
+	start := time.Now()
 	body := map[string]any{
 		"model":    a.cfg.Model,
 		"messages": messages,
@@ -101,14 +116,13 @@ func (a *Adapter) ChatStream(ctx context.Context, messages []model.LLMMessage) (
 	}
 
 	ch := make(chan model.StreamToken, 64)
-
 	go func() {
 		defer close(ch)
-
 		err := a.doStreamRequest(ctx, "POST", "/chat/completions", body, ch)
+		a.recordCall(start, "chat_stream", 0, 0, err)
 		if err != nil {
 			select {
-			case ch <- model.StreamToken{Content: fmt.Sprintf("[LLM error: %v]", err), Done: true}:
+			case ch <- model.StreamToken{Content: fmt.Sprintf("[Error: %v]", err), Done: true}:
 			default:
 			}
 		}
@@ -117,6 +131,21 @@ func (a *Adapter) ChatStream(ctx context.Context, messages []model.LLMMessage) (
 	return ch, nil
 }
 
+func (a *Adapter) recordCall(start time.Time, purpose string, promptTok, compTok int, err error) {
+	if a.onCall != nil {
+		a.onCall(CallRecord{
+			Time:             start,
+			Model:            a.cfg.Model,
+			Purpose:          purpose,
+			PromptTokens:     promptTok,
+			CompletionTokens: compTok,
+			DurationMs:       time.Since(start).Milliseconds(),
+			Success:          err == nil,
+			Error:            func() string { if err != nil { return err.Error() }; return "" }(),
+		})
+	}
+}
+
 // doRequest sends a non-streaming request and parses the response.
 func (a *Adapter) doRequest(ctx context.Context, method, path string, body map[string]any, parser func(map[string]any) error) error {
 	jsonBody, _ := json.Marshal(body)