feat: inspector page, link debug enhancements, security hardening

- Add /inspector page: visual model-accurate switch chassis diagrams
  (USF5P, USL8A, US24PRO, USPPDUP, USMINI), clickable port blocks
  with color coding (green=up, amber=PoE, cyan=uplink, grey=down),
  detail panel with stats/PoE/LLDP, LLDP-based path debug side-by-side

- Link Debug: port number badges (#N), LLDP neighbor line, PoE class/max,
  collapsible host/switch panels with sessionStorage persistence

- monitor.py: collect LLDP neighbor map + PoE class/max/mode per switch
  port; PulseClient uses requests.Session() for HTTP keep-alive; add
  shlex.quote() around interface names (defense-in-depth)

- Security: suppress buttons use data-* attrs + delegated click handler
  instead of inline onclick with Jinja2 variable interpolation; remove
  | safe filter from user-controlled fields in suppressions.html;
  setDuration() takes explicit el param instead of implicit event global

- db.py: thread-local connection reuse with ping(reconnect=True) to
  avoid a new TCP handshake per query

- .gitignore: add config.json (contains credentials), __pycache__

- README: full rewrite covering architecture, all 4 pages, alert logic,
  config reference, deployment, troubleshooting, security notes

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

templates/index.html

@@ -116,7 +116,9 @@
 
       <div class="host-actions">
         <button class="btn-sm btn-suppress"
-                onclick="openSuppressModal('host', '{{ name }}', '')"
+                data-sup-type="host"
+                data-sup-name="{{ name }}"
+                data-sup-detail=""
                 title="Suppress alerts for this host">
           🔕 Suppress
         </button>
@@ -164,7 +166,9 @@
           <td>
             {% if not d.connected %}
             <button class="btn-sm btn-suppress"
-                    onclick="openSuppressModal('unifi_device', '{{ d.name }}', '')">
+                    data-sup-type="unifi_device"
+                    data-sup-name="{{ d.name }}"
+                    data-sup-detail="">
               🔕 Suppress
             </button>
             {% endif %}
@@ -221,7 +225,9 @@
             </td>
             <td>
               <button class="btn-sm btn-suppress"
-                      onclick="openSuppressModal('{{ 'unifi_device' if e.event_type == 'unifi_device_offline' else 'interface' if e.event_type == 'interface_down' else 'host' }}', '{{ e.target_name }}', '{{ e.target_detail or '' }}')"
+                      data-sup-type="{{ 'unifi_device' if e.event_type == 'unifi_device_offline' else 'interface' if e.event_type == 'interface_down' else 'host' }}"
+                      data-sup-name="{{ e.target_name }}"
+                      data-sup-detail="{{ e.target_detail or '' }}"
                       title="Suppress">🔕</button>
             </td>
           </tr>
@@ -271,11 +277,11 @@
       <div class="form-group" style="margin-bottom:0">
         <label>Duration</label>
         <div class="duration-pills">
-          <button type="button" class="pill" onclick="setDuration(30)">30 min</button>
-          <button type="button" class="pill" onclick="setDuration(60)">1 hr</button>
-          <button type="button" class="pill" onclick="setDuration(240)">4 hr</button>
-          <button type="button" class="pill" onclick="setDuration(480)">8 hr</button>
-          <button type="button" class="pill pill-manual active" onclick="setDuration(null)">Manual ∞</button>
+          <button type="button" class="pill" onclick="setDuration(30, this)">30 min</button>
+          <button type="button" class="pill" onclick="setDuration(60, this)">1 hr</button>
+          <button type="button" class="pill" onclick="setDuration(240, this)">4 hr</button>
+          <button type="button" class="pill" onclick="setDuration(480, this)">8 hr</button>
+          <button type="button" class="pill pill-manual active" onclick="setDuration(null, this)">Manual ∞</button>
         </div>
         <input type="hidden" id="sup-expires" name="expires_minutes" value="">
         <div class="form-hint" id="duration-hint">Persists until manually removed.</div>