refactor(web): prune deprecated hosts-redirection-test markup and JS

The /etc/hosts migration method has been hidden from the UI since
before the wizard refactor — the Customize three-axis form doesn't
expose it, the suggested-plan engine never picks it, and
onCustomizeChange explicitly force-hides the legacy
#hosts-redirection-test pane. The pane was sitting in the DOM doing
nothing.

Removed:

  - The hosts-redirection-test <div> (button, result pane, header)
  - test-hosts-btn.onclick wiring in showSummary
  - The testHostsRedirection() function (orphaned once the button is
    gone)
  - The show("hosts-redirection-test", false) toggle in
    onCustomizeChange (orphaned once the pane is gone)

Backend untouched:

  - /setup/test-hosts/{deviceId} and HandleTestHostsRedirection still
    exist for API back-compat. Same pattern we used when retiring the
    XML method's self/proxied/original dropdowns — only the UI
    surface moves; the manager-level entry points stay.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pkg/service/handlers/web/index.html

@@ -673,54 +673,6 @@
                 ></div>
             </div>
 
-            <div
-                id="hosts-redirection-test"
-                style="
-                            margin: 15px 0;
-                            padding: 10px;
-                            border: 1px solid #ddd;
-                            background-color: #fff4e6;
-                            display: none;
-                        "
-            >
-                <strong>Preliminary /etc/hosts Test:</strong><br/>
-                <span style="font-size: 0.85em; color: #555"
-                >Verify the device's /etc/hosts mechanism before
-                            full migration.</span
-                >
-                <div style="margin-top: 10px">
-                    Domain: <code>custom-test-api.bose.fake</code>
-                </div>
-                <div style="margin-top: 10px">
-                    <button
-                        id="test-hosts-btn"
-                        style="
-                                    background-color: #ff9800;
-                                    color: white;
-                                    border: none;
-                                    padding: 5px 10px;
-                                    font-size: 0.9em;
-                                "
-                    >
-                        Test Hosts Redirection
-                    </button>
-                </div>
-                <div
-                    id="hosts-test-result"
-                    style="
-                                margin-top: 10px;
-                                display: none;
-                                padding: 10px;
-                                border-radius: 4px;
-                                font-family: monospace;
-                                white-space: pre-wrap;
-                                font-size: 0.85em;
-                                max-height: 200px;
-                                overflow-y: auto;
-                            "
-                ></div>
-            </div>
-
             <div
                 id="dns-redirection-test"
                 style="

pkg/service/handlers/web/js/script.js

@@ -1848,7 +1848,6 @@ async function showSummary(deviceId) {
 
         document.getElementById("test-connection-explicit-btn").onclick = () => testConnection(deviceId, true);
         document.getElementById("test-connection-trusted-btn").onclick = () => testConnection(deviceId, false);
-        document.getElementById("test-hosts-btn").onclick = () => testHostsRedirection(deviceId);
         document.getElementById("test-dns-btn").onclick = () => testDNSRedirection(deviceId);
 
         renderCustomizeForm(summary);
@@ -2404,34 +2403,6 @@ async function testConnection(deviceId, useExplicitCA) {
     }
 }
 
-async function testHostsRedirection(deviceId) {
-    const targetUrl = document.getElementById("target-domain").value;
-    const testResultDiv = document.getElementById("hosts-test-result");
-    const display = getDeviceDisplayName(deviceId);
-
-    testResultDiv.style.display = "block";
-    testResultDiv.style.backgroundColor = "#f0f0f0";
-    testResultDiv.style.color = "black";
-    testResultDiv.innerText = "Running hosts redirection test from " + display + "...\n(This may take a few seconds)";
-
-    try {
-        const query = `?target_url=${encodeURIComponent(targetUrl)}`;
-        const response = await fetch(`/setup/test-hosts/${encodeURIComponent(deviceId)}${query}`, {method: "POST"},);
-        const result = await response.json();
-
-        if (result.ok) {
-            testResultDiv.style.backgroundColor = "#ccffcc";
-            testResultDiv.innerText = "✅ " + result.message + "\n\nOutput:\n" + result.output;
-        } else {
-            testResultDiv.style.backgroundColor = "#ffcccc";
-            testResultDiv.innerText = "❌ Test failed: " + result.message + "\n\nOutput:\n" + result.output;
-        }
-    } catch (error) {
-        testResultDiv.style.backgroundColor = "#ffcccc";
-        testResultDiv.innerText = "❌ Error triggering test: " + error;
-    }
-}
-
 async function testDNSRedirection(deviceId) {
     const targetUrl = document.getElementById("target-domain").value;
     const testResultDiv = document.getElementById("dns-test-result");
@@ -3662,7 +3633,6 @@ function onCustomizeChange() {
     show("resolv-diff-row",  dns === "resolv");
     show("telnet-method-pane", flip === "telnet");
     show("dns-redirection-test", dns === "resolv");
-    show("hosts-redirection-test", false);
 
     // Validate the combination and toggle the Apply button.
     const errors = [];