Warranty phase 2: real Dell provider + settings UI + PC hero badge

- DellProvider: real Dell TechDirect lookup. OAuth2 via HTTP Basic auth,
  asset-entitlements under /PROD/sbil/eapi/v5 (the device.warranty path 404s
  for this account), map latest dated entitlement to service level + dates.
  Cache the token process-wide; Dell rate-limits the token endpoint and a
  fresh request per refresh trips a 401 cooldown. Verified against live Dell.
- Lenovo/HP stay config-shaped stubs.
- Settings: warranty_dell_* keys (category integrations); Dell Warranty Lookup
  block in System Settings > Integrations (enable + client id/secret masked +
  optional token/API URL overrides).
- WarrantyPanel takes optional pre-fetched items; PCDetail fetches once and
  feeds both the panel and a new hero warranty-status/end-date badge.
- tools/mock_dell.py for offline testing of the provider flow.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/views/settings/SystemSettings.vue

@@ -77,6 +77,86 @@
           <span>{{ zabbixMessage }}</span>
         </div>
       </div>
+
+      <div class="setting-group">
+        <h3>Dell Warranty Lookup</h3>
+        <p class="setting-description">
+          Look up Dell coverage by service tag via the Dell TechDirect Warranty API.
+          When enabled, the Refresh button on a Dell warranty pulls the current service
+          level and end date. Requires a Dell TechDirect API client id and secret.
+        </p>
+
+        <div class="setting-row">
+          <label class="toggle-label">
+            <span>Enable Dell Warranty Lookup</span>
+            <button
+              class="toggle-btn"
+              :class="{ active: settings.warranty_dell_enabled }"
+              @click="toggleSetting('warranty_dell_enabled')"
+              :disabled="saving"
+            >
+              <span class="toggle-slider"></span>
+            </button>
+          </label>
+        </div>
+
+        <div class="setting-row" v-if="settings.warranty_dell_enabled">
+          <label>
+            <span>Client ID</span>
+            <input
+              type="text"
+              v-model="settings.warranty_dell_clientid"
+              placeholder="Dell TechDirect client id"
+              @blur="saveSetting('warranty_dell_clientid', settings.warranty_dell_clientid)"
+              :disabled="saving"
+            >
+          </label>
+        </div>
+
+        <div class="setting-row" v-if="settings.warranty_dell_enabled">
+          <label>
+            <span>Client Secret</span>
+            <input
+              type="password"
+              v-model="settings.warranty_dell_clientsecret"
+              placeholder="Enter client secret"
+              @blur="saveSetting('warranty_dell_clientsecret', settings.warranty_dell_clientsecret)"
+              :disabled="saving"
+            >
+          </label>
+        </div>
+
+        <div class="setting-row" v-if="settings.warranty_dell_enabled">
+          <label>
+            <span>Token URL <small>(blank = Dell default)</small></span>
+            <input
+              type="url"
+              v-model="settings.warranty_dell_tokenurl"
+              placeholder="https://apigtwb2c.us.dell.com/auth/oauth/v2/token"
+              @blur="saveSetting('warranty_dell_tokenurl', settings.warranty_dell_tokenurl)"
+              :disabled="saving"
+            >
+          </label>
+        </div>
+
+        <div class="setting-row" v-if="settings.warranty_dell_enabled">
+          <label>
+            <span>API URL <small>(blank = Dell default)</small></span>
+            <input
+              type="url"
+              v-model="settings.warranty_dell_apiurl"
+              placeholder="https://apigtwb2c.us.dell.com/PROD/sbfxapp/device.warranty/v5/asset-entitlements"
+              @blur="saveSetting('warranty_dell_apiurl', settings.warranty_dell_apiurl)"
+              :disabled="saving"
+            >
+          </label>
+        </div>
+
+        <div class="status-indicator" v-if="settings.warranty_dell_enabled">
+          <span class="status-dot" :class="dellStatus"></span>
+          <span>{{ dellMessage }}</span>
+        </div>
+      </div>
     </div>
 
     <!-- Email Section -->
@@ -625,6 +705,11 @@ const settings = reactive({
   zabbix_enabled: false,
   zabbix_url: '',
   zabbix_token: '',
+  warranty_dell_enabled: false,
+  warranty_dell_clientid: '',
+  warranty_dell_clientsecret: '',
+  warranty_dell_tokenurl: '',
+  warranty_dell_apiurl: '',
   // Email
   smtp_enabled: false,
   smtp_host: '',
@@ -720,6 +805,20 @@ const zabbixMessage = computed(() => {
   return 'Configured (connectivity checked on first use)'
 })
 
+// Dell warranty status
+const dellStatus = computed(() => {
+  if (!settings.warranty_dell_enabled) return 'inactive'
+  if (!settings.warranty_dell_clientid || !settings.warranty_dell_clientsecret) return 'warning'
+  return 'pending'
+})
+
+const dellMessage = computed(() => {
+  if (!settings.warranty_dell_enabled) return 'Disabled'
+  if (!settings.warranty_dell_clientid) return 'Client id not configured'
+  if (!settings.warranty_dell_clientsecret) return 'Client secret not configured'
+  return 'Configured (used when you refresh a Dell warranty)'
+})
+
 // SMTP status
 const smtpStatus = computed(() => {
   if (!settings.smtp_enabled) return 'inactive'