chore(daemon): add debug logging for task lifecycle troubleshooting

Add structured logging at key points in the task completion flow:
- Daemon: log result details before sending to server, log claim cycles
- Handler: log incoming CompleteTask requests
- TaskService: log each step of CompleteTask (DB update, issue status
  sync, comment creation, payload parsing)

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

server/internal/handler/daemon.go

@@ -3,6 +3,7 @@ package handler
 import (
 	"encoding/json"
 	"fmt"
+	"log"
 	"net/http"
 	"strings"
 
@@ -206,13 +207,17 @@ func (h *Handler) CompleteTask(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	log.Printf("[Handler.CompleteTask] task=%s output_len=%d", taskID, len(req.Output))
+
 	result, _ := json.Marshal(req)
 	task, err := h.TaskService.CompleteTask(r.Context(), parseUUID(taskID), result)
 	if err != nil {
+		log.Printf("[Handler.CompleteTask] task=%s error: %v", taskID, err)
 		writeError(w, http.StatusBadRequest, err.Error())
 		return
 	}
 
+	log.Printf("[Handler.CompleteTask] task=%s completed, issue status synced", taskID)
 	writeJSON(w, http.StatusOK, taskToResponse(*task))
 }