feat(admin): 数据总览按客迹视觉V1重做（周期卡/趋势双线/渠道条形/最近访问）

Co-Authored-By: Claude Code <noreply@anthropic.com>

server/tracker/tests/test_visitors.py

@@ -78,8 +78,8 @@ def test_list_fields_and_default_bot_excluded(client, member_user):
                         "device_type", "os", "browser", "language", "first_seen_at",
                         "last_seen_at", "visit_count", "active_days", "session_count",
                         "total_stay_ms", "first_source", "last_source", "first_landing_path",
-                        "online", "channel", "platform", "variant", "search_term", "resolution",
-                        "device_model"}
+                        "last_path", "online", "channel", "platform", "variant", "search_term",
+                        "resolution", "device_model"}
     assert row["country"] == "中国" and row["os"] == "Windows" and row["browser"] == "Chrome"
     assert row["session_count"] == 2
     assert row["total_stay_ms"] == 150000            # 120000+30000，有效停留口径
@@ -146,6 +146,26 @@ def test_list_site_fields_and_site_filter(client, member_user):
     assert d["total"] == 1 and [x["visitor_id"] for x in d["list"]] == ["vb"]  # 只剩本站访客
 
 
+def test_list_last_path(client, member_user):
+    """列表行 last_path：该访客最近一条事件的 path（Subquery 注解，无 N+1）；
+    无事件访客为空串。"""
+    _auth(client, member_user)
+    site = Site.objects.create(name="s", domains=["a.com"])
+    v1 = _visitor(site, "v1", last_seen=timezone.now())
+    v2 = _visitor(site, "v2", last_seen=timezone.now() - timedelta(hours=1))
+    s1 = _session(site, v1, "s1", at=NOW - timedelta(hours=2))
+    _event(site, v1, s1, "e1", "page_view", NOW - timedelta(hours=2), path="/old")
+    _event(site, v1, s1, "e2", "page_view", NOW - timedelta(minutes=90), path="/stay")
+    _event(site, v1, s1, "e3", "page_stay", NOW - timedelta(minutes=30), path="/stay",
+           active_ms=1000)   # occurred_at 早于 e2 → 不改判"最近"
+    _event(site, v1, s1, "e4", "page_view", NOW, path="/newest")
+
+    d = client.get("/api/admin/visitors").json()["data"]
+    by_id = {x["visitor_id"]: x for x in d["list"]}
+    assert by_id["v1"]["last_path"] == "/newest"   # 最近一条事件的 path
+    assert by_id["v2"]["last_path"] == ""          # 无事件 → 空串（前端显示 —）
+
+
 def test_list_site_not_found(client, member_user):
     _auth(client, member_user)
     site = Site.objects.create(name="s", domains=["a.com"])
@@ -198,6 +218,7 @@ def test_detail_shape(client, member_user):
     assert d["session_count"] == 2 and d["total_stay_ms"] == 90000
     assert d["first_source"] == "google.com"
     assert d["last_source"] == "wechat"            # 最近会话 s-new：referrer 空 → utm 兜底
+    assert d["last_path"] == "/b"                  # 最近一条事件 e3 的 path
     assert [s["session_id"] for s in d["sessions"]] == ["s-new", "s-old"]   # 最近在前
     srow = d["sessions"][0]
     assert set(srow) == {"session_id", "started_at", "ended_at", "referrer_domain", "utm",