feat: surface BMC collection errors in parse-errors panel and event log

When Inspur component.log sections return {"error":"...","code":N} instead
of hardware data, the parser now:
- stores them in AnalysisResult.CollectionErrors (new model field)
- mirrors each one into result.Events with Source="BMC/<section>"
  so the chart viewer event table shows the specific BMC module
- feeds them into /api/parse-errors as bmc_collection_error entries

UI adds a collapsible "Collection diagnostics" panel below the chart
iframe (outside /chart) that appears when /api/parse-errors returns
any items; resets on data clear.

Affected sections in this dump: HDD (1458), PCIe Devices (1458),
Network Adapters (1458), Disk Backplane.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/templates/index.html

@@ -170,6 +170,25 @@
                     </iframe>
                 </div>
             </section>
+            <section id="parse-errors-section" class="parse-errors-section hidden">
+                <div class="parse-errors-header" onclick="toggleParseErrors()">
+                    <span id="parse-errors-title">Collection warnings</span>
+                    <span id="parse-errors-toggle" class="parse-errors-toggle">▲</span>
+                </div>
+                <div id="parse-errors-body" class="parse-errors-body">
+                    <table class="parse-errors-table">
+                        <thead>
+                            <tr>
+                                <th>Source</th>
+                                <th>Section</th>
+                                <th>Message</th>
+                                <th>Detail</th>
+                            </tr>
+                        </thead>
+                        <tbody id="parse-errors-rows"></tbody>
+                    </table>
+                </div>
+            </section>
         </section>
     </main>