Align instance dashboard with hub snapshot+SSE pattern.

Background poll builds a memory snapshot; the page reads snapshot and refreshes on SSE instead of hitting heavy exchange APIs on each load.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/instance/templates/dashboard_panel.html

@@ -3,7 +3,7 @@
     <div class="inst-dash-head">
         <div>
             <h2 style="margin-bottom:4px">数据看板</h2>
-            <p class="muted inst-dash-desc">本户活跃监控总览 · 只读 · 无数据的区块不显示 · 有数据按表格展示</p>
+            <p class="muted inst-dash-desc">本户活跃监控总览 · 只读 · 后台快照 + SSE · 无数据的区块不显示</p>
         </div>
         <div class="inst-dash-head-actions">
             <span class="muted inst-dash-updated" id="inst-dash-updated">—</span>

lib/instance/templates/embed_shell.html

@@ -111,7 +111,7 @@ const ORDER_ENTRY_MODEL_CODE_TO_CATEGORY = {{ entry_model_code_to_category | toj
 {% include 'embed_boot_scripts.html' %}
 <script src="/static/records_review_page.js?v=2"></script>
 <script src="/static/options_expiry_countdown.js?v=1"></script>
-<script src="/static/instance_dashboard.js?v=3"></script>
+<script src="/static/instance_dashboard.js?v=4"></script>
 <script>
 window.__INSTANCE_DISPLAY__ = {{ display | tojson }};
 </script>

lib/instance/templates/index.html

@@ -2011,7 +2011,7 @@ setInterval(refreshPriceSnapshotConditional, {{ price_refresh_seconds * 1000 }})
 </script>
 <script src="/static/records_review_page.js?v=2"></script>
 <script src="/static/options_expiry_countdown.js?v=1"></script>
-<script src="/static/instance_dashboard.js?v=3"></script>
+<script src="/static/instance_dashboard.js?v=4"></script>
 <script>
 window.__INSTANCE_DISPLAY__ = {{ display | tojson }};
 {% if page == 'dashboard' %}