Stage 17 (#15): admin users people/robots toggle + display-name & external-id glob filters

- account.ListUsers/CountUsers with a UserFilter: people vs robots (by a robot identity),
  case-insensitive '*'/'?' glob masks on display_name and any identity's external_id
- admin users list shows the real kind (robot/guest/registered), defaults to people,
  with a People/Robots toggle + a filter form; pager preserves the filter
- integration test for the filter; SQL verified against the live contour DB

backend/internal/adminconsole/templates/pages/users.gohtml

@@ -1,6 +1,16 @@
 {{define "content" -}}
 <h1>Users</h1>
 {{with .Data}}
+<nav class="subnav">
+<a href="/_gm/users"{{if not .Robots}} class="active"{{end}}>People</a> ·
+<a href="/_gm/users?kind=robots"{{if .Robots}} class="active"{{end}}>Robots</a>
+</nav>
+<form class="form" method="get" action="/_gm/users">
+{{if .Robots}}<input type="hidden" name="kind" value="robots">{{end}}
+<input name="name" value="{{.NameMask}}" placeholder="display name mask (* ?)">
+<input name="ext" value="{{.ExternalIDMask}}" placeholder="external id mask (* ?)">
+<button type="submit">Filter</button>
+</form>
 <table class="list">
 <thead><tr><th>Account</th><th>Display name</th><th>Kind</th><th>Lang</th><th>Created</th><th title="per-move think time across all games">Move min</th><th>avg</th><th>max</th></tr></thead>
 <tbody>
@@ -19,9 +29,9 @@
 </tbody>
 </table>
 <nav class="pager">
-{{if .Pager.HasPrev}}<a href="/_gm/users?page={{.Pager.PrevPage}}">&laquo; prev</a>{{end}}
+{{if .Pager.HasPrev}}<a href="/_gm/users?{{.FilterQuery}}&amp;page={{.Pager.PrevPage}}">&laquo; prev</a>{{end}}
 <span>page {{.Pager.Page}} · {{.Pager.Total}} total</span>
-{{if .Pager.HasNext}}<a href="/_gm/users?page={{.Pager.NextPage}}">next &raquo;</a>{{end}}
+{{if .Pager.HasNext}}<a href="/_gm/users?{{.FilterQuery}}&amp;page={{.Pager.NextPage}}">next &raquo;</a>{{end}}
 </nav>
 {{end}}
 {{- end}}