feat(adminui): F15.2 batch 1 — Namespace + DriverInstance live-edit CRUD

Pattern proof for the live-edit forms gated by Phases A–D's read views.
Each entity gets a single edit page handling both create (route param
omitted) and update (route param present) modes, with RowVersion-based
optimistic concurrency checked against EF Core's
DbUpdateConcurrencyException.

Pattern:
- @page "/clusters/{id}/<thing>/new"
- @page "/clusters/{id}/<thing>/{rowId}"
- IsNew computed from rowId presence
- EditForm + DataAnnotations validation
- byte[] RowVersion stashed on FormModel; assigned to
  Entry(e).Property(e => e.RowVersion).OriginalValue before SaveChanges
- Delete button (edit mode only) flows through the same RowVersion check
- Concurrency conflict surfaces as an inline error panel; user reloads

This batch:
- NamespaceEdit.razor          — small entity, validates the pattern
- DriverEdit.razor             — keystone for everything downstream
                                 (Equipment/Tag/VirtualTag/ScriptedAlarm),
                                 JSON config editor per Q1 with reformat
                                 on save and validation pre-flight
- ClusterNamespaces row gains an Edit button + New action
- ClusterDrivers expanded view gains an Edit button + New action

Equipment/UnsArea/UnsLine/Tag/ACL/VirtualTag/ScriptedAlarm/Script forms
follow this same template in subsequent F15.2 batches.

All 9 integration tests still green; no v2 test regressions.

src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Pages/Clusters/ClusterNamespaces.razor

@@ -8,6 +8,7 @@
 
 <div class="d-flex justify-content-between align-items-center mb-3">
     <h4 class="mb-0">Namespaces &middot; <span class="mono">@ClusterId</span></h4>
+    <a href="/clusters/@ClusterId/namespaces/new" class="btn btn-primary btn-sm">New namespace</a>
 </div>
 
 <ClusterNav ClusterId="@ClusterId" ActiveTab="namespaces" />
@@ -41,6 +42,7 @@ else
                             <th>URI</th>
                             <th>Status</th>
                             <th>Notes</th>
+                            <th></th>
                         </tr>
                     </thead>
                     <tbody>
@@ -55,6 +57,7 @@ else
                                     else { <span class="chip chip-idle">Disabled</span> }
                                 </td>
                                 <td class="text-muted small">@(n.Notes ?? "")</td>
+                                <td><a href="/clusters/@ClusterId/namespaces/@n.NamespaceId" class="btn btn-sm btn-outline-primary">Edit</a></td>
                             </tr>
                         }
                     </tbody>