Warranty form: vendor combobox + clearer "Lookup source" label

- Vendor is now a datalist combobox seeded from the site vendor catalog
  (/api/vendors), so users pick a known vendor instead of retyping it, while
  still allowing free text. Kept as a string, not an FK, to keep the warranty
  plugin decoupled from core.
- Renamed the "Provider" select to "Lookup source" with helper text. It was
  confusingly synonymous with Vendor; it actually means where coverage data
  comes from (manual entry vs a maker's warranty API that supports Refresh).

frontend/src/views/warranty/WarrantiesList.vue

@@ -82,16 +82,22 @@
             <div class="form-row">
               <div class="form-group">
                 <label>Vendor *</label>
-                <input v-model="form.vendor" type="text" class="form-control" maxlength="100" required />
+                <input v-model="form.vendor" type="text" class="form-control" maxlength="100" required
+                       list="warranty-vendor-list" placeholder="e.g. Dell" />
+                <datalist id="warranty-vendor-list">
+                  <option v-for="name in vendorNames" :key="name" :value="name" />
+                </datalist>
+                <small class="muted">Who backs the warranty. Pick a known vendor or type a new one.</small>
               </div>
               <div class="form-group">
-                <label>Provider</label>
+                <label>Lookup source</label>
                 <select v-model="form.provider" class="form-control">
-                  <option value="manual">Manual</option>
-                  <option value="dell">Dell</option>
-                  <option value="lenovo">Lenovo</option>
-                  <option value="hp">HP</option>
+                  <option value="manual">Manual entry</option>
+                  <option value="dell">Dell (auto-refresh)</option>
+                  <option value="lenovo">Lenovo (auto-refresh)</option>
+                  <option value="hp">HP (auto-refresh)</option>
                 </select>
+                <small class="muted">Where coverage data comes from. Non-manual sources can be refreshed from the maker's warranty API.</small>
               </div>
             </div>
             <div class="form-row">
@@ -155,7 +161,7 @@
 import { ref, computed, watch, onMounted } from 'vue'
 import { useRoute } from 'vue-router'
 import { colorStyle } from '@/utils/colorStyle'
-import { warrantyApi, assetsApi } from '../../api'
+import { warrantyApi, assetsApi, vendorsApi } from '../../api'
 import { useToast } from '../../composables/toast'
 import { apiError } from '../../utils/apiError'
 
@@ -196,6 +202,8 @@ const form = ref(blankForm())
 const selectedAssets = ref([])
 const assetQuery = ref('')
 const assetResults = ref([])
+// Suggestions for the Vendor combobox, pulled from the site vendor catalog.
+const vendorNames = ref([])
 
 function blankForm() {
   return { vendor: '', provider: 'manual', servicetag: '', servicelevel: '', startdate: '', enddate: '', notes: '' }
@@ -215,6 +223,7 @@ function assetLink(a) {
 
 onMounted(async () => {
   await loadData()
+  loadVendors()
   // Deep-link from an asset detail page: open the add modal pre-linked to it.
   const addfor = route.query.addfor
   if (addfor) {
@@ -229,6 +238,18 @@ onMounted(async () => {
   }
 })
 
+async function loadVendors() {
+  // Best-effort: the combobox still accepts free text if this fails.
+  try {
+    const response = await vendorsApi.list({ per_page: 1000 })
+    const rows = response.data.data
+    const list = Array.isArray(rows) ? rows : (rows.items || [])
+    vendorNames.value = list.map(v => v.vendor || v.name).filter(Boolean).sort()
+  } catch (err) {
+    vendorNames.value = []
+  }
+}
+
 async function loadData() {
   loading.value = true
   try {