Add DHCP reservations to the web UI, split out a fast webui test

The DHCP page edits the reservations per LAN (checked like the module's
assertions) and offers active clients for reservation. The web UI checks
that need no installed system moved from apply.nix into webui.nix (one
node, under a minute); apply.nix shares one apply for the pool change and
a reservation.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AeFqV9dZrK6nipHkPfyM4F

pkgs/router-webui/templates/dhcp.html

@@ -0,0 +1,44 @@
+{{define "content"}}
+{{with .Data}}
+{{$e := .Errors}}
+<form method="post" action="/dhcp">
+  <input type="hidden" name="csrf" value="{{$.CSRF}}">
+  <fieldset>
+    <legend>Reservations</legend>
+    {{if not .LANs}}<p class="field-error">No LAN serves DHCP; enable it on the Network page first.</p>{{end}}
+    <input type="hidden" name="rows" value="{{len .Rows}}">
+    <table>
+      <tr><th>LAN</th><th>Name</th><th>MAC</th><th>Address</th><th>Remove</th></tr>
+      {{range $i, $r := .Rows}}
+      <tr>
+        <td><select name="res.{{$i}}.lan">
+          {{range $.Data.LANs}}<option value="{{.}}" {{if eq . $r.LAN}}selected{{end}}>{{.}}</option>{{end}}
+        </select></td>
+        <td><input name="res.{{$i}}.name" value="{{$r.Name}}" size="14" placeholder="new"></td>
+        <td><input name="res.{{$i}}.mac" value="{{$r.MAC}}" size="17" spellcheck="false" placeholder="aa:bb:cc:dd:ee:ff"></td>
+        <td><input name="res.{{$i}}.address" value="{{$r.Address}}" size="13"></td>
+        <td>{{if $r.Name}}<input type="checkbox" name="res.{{$i}}.remove">{{end}}</td>
+      </tr>
+      {{range $f := list "lan" "name" "mac" "address"}}{{with index $e (printf "res[%d].%s" $i $f)}}<tr><td colspan="5" class="field-error">{{$f}}: {{.}}</td></tr>{{end}}{{end}}
+      {{end}}
+    </table>
+    <p class="hint">Fill in the last row to add one. The name is also sent to the client and published in DNS.
+       The address should be outside the pool.</p>
+  </fieldset>
+  <button>Save</button>
+</form>
+
+<section>
+  <h2>Clients without a reservation</h2>
+  {{if .Clients}}
+  <div class="scroll">
+  <table class="leases">
+    <tr><th>Name</th><th>Address</th><th>MAC</th><th>LAN</th><th></th></tr>
+    {{range .Clients}}<tr><td>{{or .Hostname "–"}}</td><td>{{.Address}}</td><td><code>{{.MAC}}</code></td><td>{{.LAN}}</td>
+      <td><a href="/dhcp?lan={{.LAN | urlquery}}&amp;name={{.Hostname | urlquery}}&amp;mac={{.MAC | urlquery}}&amp;address={{.Address | urlquery}}">Reserve</a></td></tr>{{end}}
+  </table>
+  </div>
+  {{else}}<p class="muted">No active leases.</p>{{end}}
+</section>
+{{end}}
+{{end}}

pkgs/router-webui/templates/layout.html

@@ -14,6 +14,7 @@
   <nav>
     <a href="/">Overview</a>
     <a href="/network">Network</a>
+    <a href="/dhcp">DHCP</a>
     <a href="/update">Update</a>
     <a href="/advanced">Advanced</a>
     <form method="post" action="/logout"><input type="hidden" name="csrf" value="{{.CSRF}}"><button class="link">Log out</button></form>

pkgs/router-webui/templates/network.html

@@ -65,7 +65,7 @@
       {{range $f := list "name" "interface" "vlan" "address" "prefix" "poolStart" "poolEnd"}}{{with index $e (printf "lans[%d].%s" $i $f)}}<tr><td colspan="11" class="field-error">{{$f}}: {{.}}</td></tr>{{end}}{{end}}
       {{end}}
     </table>
-    <p class="hint">Fill in the last row to add a LAN. Other LAN settings (reservations, zones, a fixed IPv6 address) are kept; edit them under Advanced.</p>
+    <p class="hint">Fill in the last row to add a LAN. Other LAN settings (zones, a fixed IPv6 address) are kept; edit them under Advanced.</p>
   </fieldset>
 
   <button>Save</button>