feat(adminui): F15 Phase B — cluster CRUD + Overview/Redundancy routes

- ClustersList (/clusters) — table view, row-click opens detail
- NewCluster (/clusters/new) — EditForm with DataAnnotations; redundancy
  mode + node-count coupling enforced client-side (None→1, Warm/Hot→2);
  CreatedBy taken from AuthenticationStateProvider
- ClusterOverview (/clusters/{id}) — cluster details + last-deployment
  badge + node list. Per Q3, the legacy 10-tab monolith is split into
  separate routes; this page hosts the Overview "tab" as its primary slot
- ClusterRedundancy (/clusters/{id}/redundancy) — static ServiceLevelBase
  config view; live ServiceLevel comes via RedundancyStateActor DPS topic
  (deferred to its own follow-up once the SignalR bridge lands)

The other 8 v1 cluster tabs (Equipment, UNS, Namespaces, Drivers, Tags,
ACLs, ScriptedAlarms, Scripts, Audit) land in Phase C/D.

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

@@ -0,0 +1,141 @@
+@page "/clusters/new"
+@attribute [Microsoft.AspNetCore.Authorization.Authorize]
+@rendermode RenderMode.InteractiveServer
+@using Microsoft.AspNetCore.Components.Forms
+@using Microsoft.EntityFrameworkCore
+@using ZB.MOM.WW.OtOpcUa.Configuration
+@using ZB.MOM.WW.OtOpcUa.Configuration.Entities
+@using ZB.MOM.WW.OtOpcUa.Configuration.Enums
+@inject IDbContextFactory<OtOpcUaConfigDbContext> DbFactory
+@inject NavigationManager Nav
+@inject AuthenticationStateProvider AuthState
+
+<div class="d-flex justify-content-between align-items-center mb-3">
+    <h4 class="mb-0">New cluster</h4>
+    <a href="/clusters" class="btn btn-outline-secondary btn-sm">Cancel</a>
+</div>
+
+<EditForm Model="_form" OnValidSubmit="SubmitAsync" FormName="newCluster">
+    <DataAnnotationsValidator />
+    <section class="panel rise" style="animation-delay:.02s">
+        <div class="panel-head">Identity</div>
+        <div style="padding:1rem">
+            <div class="mb-3">
+                <label class="form-label" for="clusterId">Cluster ID</label>
+                <InputText id="clusterId" @bind-Value="_form.ClusterId" class="form-control form-control-sm mono"
+                           placeholder="LINE3-OPCUA" />
+            </div>
+            <div class="mb-3">
+                <label class="form-label" for="name">Name</label>
+                <InputText id="name" @bind-Value="_form.Name" class="form-control form-control-sm" />
+            </div>
+            <div class="row">
+                <div class="col-md-6 mb-3">
+                    <label class="form-label" for="enterprise">Enterprise</label>
+                    <InputText id="enterprise" @bind-Value="_form.Enterprise" class="form-control form-control-sm"
+                               placeholder="zb" />
+                </div>
+                <div class="col-md-6 mb-3">
+                    <label class="form-label" for="site">Site</label>
+                    <InputText id="site" @bind-Value="_form.Site" class="form-control form-control-sm"
+                               placeholder="warsaw-west" />
+                </div>
+            </div>
+        </div>
+    </section>
+
+    <section class="panel rise mt-3" style="animation-delay:.08s">
+        <div class="panel-head">Topology</div>
+        <div style="padding:1rem">
+            <div class="mb-3">
+                <label class="form-label" for="redundancy">Redundancy mode</label>
+                <InputSelect id="redundancy" @bind-Value="_form.RedundancyMode" class="form-select form-select-sm">
+                    <option value="@RedundancyMode.None">None (1 node)</option>
+                    <option value="@RedundancyMode.Warm">Warm (2 nodes, non-transparent)</option>
+                    <option value="@RedundancyMode.Hot">Hot (2 nodes, non-transparent)</option>
+                </InputSelect>
+                <div class="form-text">NodeCount is implied — 1 for None, 2 for Warm/Hot.</div>
+            </div>
+            <div class="mb-3">
+                <label class="form-label" for="notes">Notes</label>
+                <InputTextArea id="notes" @bind-Value="_form.Notes" class="form-control form-control-sm" rows="3" />
+            </div>
+        </div>
+    </section>
+
+    @if (!string.IsNullOrWhiteSpace(_error))
+    {
+        <div class="panel notice mt-3">@_error</div>
+    }
+
+    <div class="mt-3 d-flex gap-2">
+        <button type="submit" class="btn btn-primary" disabled="@_busy">
+            @if (_busy) { <span class="spinner-border spinner-border-sm me-1"></span> }
+            Create cluster
+        </button>
+        <a href="/clusters" class="btn btn-outline-secondary">Cancel</a>
+    </div>
+</EditForm>
+
+@code {
+    private FormModel _form = new();
+    private string? _error;
+    private bool _busy;
+
+    private async Task SubmitAsync()
+    {
+        _busy = true;
+        _error = null;
+        try
+        {
+            await using var db = await DbFactory.CreateDbContextAsync();
+            if (await db.ServerClusters.AnyAsync(c => c.ClusterId == _form.ClusterId))
+            {
+                _error = $"Cluster '{_form.ClusterId}' already exists.";
+                return;
+            }
+
+            var auth = await AuthState.GetAuthenticationStateAsync();
+            var createdBy = auth.User.Identity?.Name ?? "(anonymous)";
+
+            var entity = new ServerCluster
+            {
+                ClusterId = _form.ClusterId,
+                Name = _form.Name,
+                Enterprise = _form.Enterprise,
+                Site = _form.Site,
+                RedundancyMode = _form.RedundancyMode,
+                NodeCount = _form.RedundancyMode == RedundancyMode.None ? (byte)1 : (byte)2,
+                Notes = string.IsNullOrWhiteSpace(_form.Notes) ? null : _form.Notes,
+                Enabled = true,
+                CreatedAt = DateTime.UtcNow,
+                CreatedBy = createdBy,
+            };
+            db.ServerClusters.Add(entity);
+            await db.SaveChangesAsync();
+            Nav.NavigateTo($"/clusters/{entity.ClusterId}");
+        }
+        catch (Exception ex)
+        {
+            _error = ex.Message;
+        }
+        finally
+        {
+            _busy = false;
+        }
+    }
+
+    private sealed class FormModel
+    {
+        [System.ComponentModel.DataAnnotations.Required, System.ComponentModel.DataAnnotations.RegularExpression("^[A-Z0-9_-]+$", ErrorMessage = "Use uppercase letters, digits, dash, underscore.")]
+        public string ClusterId { get; set; } = "";
+        [System.ComponentModel.DataAnnotations.Required]
+        public string Name { get; set; } = "";
+        [System.ComponentModel.DataAnnotations.Required]
+        public string Enterprise { get; set; } = "zb";
+        [System.ComponentModel.DataAnnotations.Required]
+        public string Site { get; set; } = "";
+        public RedundancyMode RedundancyMode { get; set; } = RedundancyMode.None;
+        public string? Notes { get; set; }
+    }
+}