init: tianyan-edge edge agent with Ascend NPU inference backend

- Go main process: stream ingestor, infer client, event uploader,
  heartbeat, config agent, OTA agent
- Python inference server rewritten to use CANN ACL (acl module)
  replacing ultralytics/PyTorch; supports YOLOv8 raw and YOLOv10
  NMS-free output formats via OUTPUT_FORMAT env var
- systemd services for edge-agent and edge-infer
- build/install/package scripts targeting arm64

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

internal/control/heartbeat.go

@@ -0,0 +1,54 @@
+package control
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"time"
+
+	"tianyan-edge/internal/config"
+)
+
+type Heartbeat struct {
+	cfg *config.Config
+}
+
+func NewHeartbeat(cfg *config.Config) *Heartbeat {
+	return &Heartbeat{cfg: cfg}
+}
+
+func (h *Heartbeat) Run(ctx context.Context) {
+	client := &http.Client{Timeout: 5 * time.Second}
+	ticker := time.NewTicker(30 * time.Second)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			h.send(client)
+		}
+	}
+}
+
+func (h *Heartbeat) send(client *http.Client) {
+	payload := map[string]any{
+		"edge_id": h.cfg.EdgeID,
+		"version": h.cfg.Version,
+		"ts":      float64(time.Now().UnixMilli()) / 1000.0,
+	}
+	body, _ := json.Marshal(payload)
+	url := fmt.Sprintf("%s/api/v1/edge/heartbeat", h.cfg.CloudURL)
+	req, _ := http.NewRequest(http.MethodPost, url, bytes.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", "Bearer "+h.cfg.EdgeToken)
+	resp, err := client.Do(req)
+	if err != nil {
+		log.Printf("heartbeat: %v", err)
+		return
+	}
+	resp.Body.Close()
+}