fix: close the eSIM panel so the Test script pill shows its panel (v3.6.1)

#phone-sub-esim was missing its closing </div> before #phone-sub-test, so
the browser parsed the test panel (and everything after) as a child of the
eSIM panel.  Clicking Test script unhid the panel itself, but its hidden
ancestor kept it invisible - the pill has never shown a panel in a real
browser since it was added (v3.5.11).  The eSIM LPA pill conversely showed
the whole test editor below its own fields.

The old whole-file div-count test stayed green because the inline script's
template strings happen to contain one extra </div>; the real markup was
409 opens vs 408 closes.

- add the missing </div>.
- html.test.js: count divs on the markup only (scripts excluded) and add a
  structural walk (stray end tags, cross-nesting, unclosed elements, HTML
  optional end tags honoured) over index.html, help.html and help-ru.html,
  plus a Simulator-panel sibling-depth check.  Run this for every HTML edit.
- the walk immediately found the same class of bug in both help pages: six
  unclosed <section> chapters each; closed them.
- AGENTS: the HTML structure test is now part of the working conventions.

602 frontend / 482 Python green; version 3.6.1; sw simple-v274.

frontend/help.html

@@ -49,6 +49,7 @@
 	</ul>
 
 
+</section>
 <section class="mb-10">
 	<h2 id="c-apdu" class="text-xl font-semibold mb-3 border-b border-gray-300 dark:border-slate-700 pb-1">2. Remote APDU tab</h2>
 	<p class="mb-3">Builds command APDUs (C-APDUs). Six sub-tabs cover different card generations, command sets and decoding tools: <strong>SIM RFM</strong>, <strong>USIM RFM</strong>, <strong>RAM/GP</strong>, <strong>Expanded Script</strong>, <strong>Push commands</strong>, and <strong>Parser</strong> &mdash; the last with the <strong>C-APDU Parser</strong> and <strong>R-APDU parser</strong> sub-pills.</p>
@@ -274,6 +275,7 @@
 	</ul>
 
 
+</section>
 <section class="mb-10">
 	<h2 id="scp80" class="text-xl font-semibold mb-3 border-b border-gray-300 dark:border-slate-700 pb-1">3. SCP80 tab</h2>
 	<p class="mb-3">The <strong>SCP80</strong> top-level tab groups the SCP80-related views. It is switched by two pills: <strong>Secured Packet</strong> and <strong>RAM</strong>. Assembles SCP80 secured packets per ETSI TS 102 225. When a card is equipped the server reads its <strong>EF.ICCID</strong> (2FE2); if a card preset carries the same number (digits, or the raw EF hex), it is selected automatically in both views.</p>
@@ -333,6 +335,7 @@
 	<p class="text-sm mb-3">Delete confirms via a browser prompt before sending the GP <code class="font-mono text-sm">DELETE</code> command via SCP80. The explorer auto-refreshes after a successful deletion.</p>
 
 
+</section>
 <section class="mb-10">
 	<h2 id="cards" class="text-xl font-semibold mb-3 border-b border-gray-300 dark:border-slate-700 pb-1">4. Cards tab</h2>
 	<p class="mb-2">Stores card presets locally in the browser (<code class="font-mono text-sm">localStorage</code>) so the Secured Packet view can auto-fill keys and parameters, and so the SCP81 HTTP OTA listener can look up PSK keys. Cards is a top-level tab. When the card is equipped its EF.ICCID is read and the preset with the same ICCID is selected automatically in both SCP80 views. The form groups the fields into two bordered blocks: <strong>SCP80 (GSM 03.48, ETSI TS 102 225)</strong> (KIc/KID, SPI1/SPI2, the ISD/UICC RFM/ADF RFM TARs, counter and keys) and <strong>SCP81 (HTTP OTA)</strong> (the PSK identity/key pair with the key-selection note). The optional <strong>ADM</strong> field sits in the top row and is stored for later use by the file manager. The header shows gray <strong>SCP80</strong>/<strong>SCP81</strong> markers and a key glyph on the ADM badge when the preset matching the equipped card's ICCID has those settings filled in.</p>
@@ -438,6 +441,7 @@
 
 
 
+</section>
 <section class="mb-10">
 	<h2 id="profiler" class="text-xl font-semibold mb-3 border-b border-gray-300 dark:border-slate-700 pb-1">7. Profiler</h2>
 	<p class="text-sm mb-2">Verifies that a card matches a named <strong>profile</strong> — an ordered set of rules describing the expected file system and (optionally) file contents. Profiles are stored in <code class="font-mono text-sm">localStorage</code>.</p>
@@ -621,6 +625,7 @@ pysim-simple-server --http-port 8080</pre>
 	<p class="text-sm mb-3">If the PWA is served from a public HTTPS host (e.g. <code class="font-mono text-sm">https://simple.example.com</code>), two things are required to reach a local card server: (1) the server must answer the preflight with <code class="font-mono text-sm">Access-Control-Allow-Private-Network: true</code> (pysim-simple-server &ge; 1.6.1 does this automatically), and (2) the browser must be allowed to access the local network &mdash; in Chrome/Edge/Vivaldi: Site settings &rarr; Local network access &rarr; allow the site (or accept the permission prompt). Without the browser permission, the request to <code class="font-mono text-sm">127.0.0.1</code> is blocked before any preflight is sent.</p>
 
 
+</section>
 <section class="mb-10">
 	<h2 id="compatibility" class="text-xl font-semibold mb-3 border-b border-gray-300 dark:border-slate-700 pb-1">10. Version compatibility</h2>
 	<table class="w-full text-sm mb-3 border-collapse">
@@ -634,6 +639,8 @@ pysim-simple-server --http-port 8080</pre>
 	<p class="text-sm">The PWA checks the server version on connect via <code class="font-mono text-sm">GET /api/version</code> and compares the major version (e.g. 3.x PWA with a 3.x server; a 2.x server is flagged as outdated).</p>
 
 
+</section>
+
 </main>
 </div>