fix(panel): /edit 404 on macOS — systemd timer path guard

edit_source checked news-harvester@<name>.timer existence (Linux layout);
on macOS schedules are LaunchAgents plists so the edit page always 404ed.
Use pl.schedule_state/schedule_times (platform layer) for the guard and
current time instead.

web/app.py

@@ -863,13 +863,12 @@ def add_source():
 def edit_source(name):
     if not re.match(r"^[a-zA-Z0-9_-]+$", name):
         abort(404)
-    timer_path = SYSTEMD_DIR / f"news-harvester@{name}.timer"
-    if not timer_path.exists():
+    # 平台无关:macOS 调度是 LaunchAgents plist,旧代码检查 systemd timer 路径导致永远 404
+    if pl.schedule_state(name) == "none":
         abort(404)
 
     if request.method == "GET":
-        timer_name = f"news-harvester@{name}.timer"
-        current_time = read_oncalendar_from_systemd(timer_name) or parse_timer_file(timer_path)
+        current_time = ",".join(t for t in pl.schedule_times(name).split(",") if t.strip()) or "-"
         conf = read_conf(name)
         return render_template("edit.html", name=name, current_time=current_time, conf=conf,
                                providers=get_providers())
@@ -884,8 +883,7 @@ def edit_source(name):
 
     if not valid_run_times(time):
         flash("时间格式应为 HH:MM，多个时间用逗号分隔", "error")
-        timer_name = f"news-harvester@{name}.timer"
-        current_time = read_oncalendar_from_systemd(timer_name) or parse_timer_file(timer_path)
+        current_time = ",".join(t for t in pl.schedule_times(name).split(",") if t.strip()) or "-"
         conf = read_conf(name)
         return render_template("edit.html", name=name, current_time=current_time, conf=conf,
                                providers=get_providers())