perf(search): prefix-by-default Deployments and config-audit search; bounded Contains opt-in (ScadaBridge#50)

Deployments free-text search and the config-audit EntityName filter no longer
emit LIKE '%term%' by default. Prefix (LIKE 'term%') is the default; substring
is an explicit opt-in (DeploymentSearchMode.Contains / entityNameContains)
always bounded by a DeployedAt/Timestamp window (explicit, else 30 days).
Migration PrefixSearchIndexes adds DeployedBy, RevisionHash and EntityName
indexes. Deployments page gains a 'Match anywhere' checkbox.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Pages/Deployment/Deployments.razor

@@ -75,6 +75,15 @@
                            data-test="deploy-search"
                            value="@_searchInput"
                            @oninput="OnSearchInput" />
+                    <div class="form-check mt-1">
+                        <input id="dep-search-contains" type="checkbox" class="form-check-input"
+                               data-test="deploy-search-contains"
+                               checked="@_searchContains"
+                               @onchange="SetSearchContainsAsync" />
+                        <label class="form-check-label small text-muted" for="dep-search-contains">
+                            Match anywhere in the text (last 30 days only; default matches the start)
+                        </label>
+                    </div>
                 </div>
                 <div class="col-auto">
                     <button class="btn btn-outline-secondary btn-sm" data-test="deploy-clear-filters"
@@ -522,6 +531,19 @@
         }
     }
 
+    /// <summary>
+    /// Opt-in substring search. Scans, so the repository bounds it to the last 30 days
+    /// (ScadaBridge#50); the default is an index-friendly prefix match.
+    /// </summary>
+    private bool _searchContains;
+
+    private async Task SetSearchContainsAsync(ChangeEventArgs e)
+    {
+        _searchContains = e.Value is true;
+        _currentPage = 1;
+        await LoadDataAsync();
+    }
+
     private async Task SetStatusFilterAsync(DeploymentStatus? status)
     {
         // Clicking the active tile clears it — a toggle, so the tiles are both the
@@ -536,6 +558,7 @@
         _statusFilter = null;
         _searchInput = string.Empty;
         _appliedSearch = string.Empty;
+        _searchContains = false;
         _currentPage = 1;
 
         // A cleared box must not be re-queried by an armed keystroke timer.
@@ -587,7 +610,8 @@
             var filter = new DeploymentListFilter(
                 Status: _statusFilter,
                 Search: _appliedSearch,
-                SiteIdScope: siteScope);
+                SiteIdScope: siteScope,
+                SearchMode: _searchContains ? DeploymentSearchMode.Contains : DeploymentSearchMode.Prefix);
 
             var page = await DeploymentManagerRepository
                 .QueryDeploymentListPageAsync(filter, pageToQuery, PageSize);