fix(search): remove double hash in channel names, add FTS5 syntax help

Channel names from device already include # prefix — removed hardcoded #
from search results badge. Added (?) help button with search syntax
examples and link to FTS5 docs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/static/js/app.js

@@ -3777,6 +3777,15 @@ function initializeSearch() {
     const btn = document.getElementById('searchBtn');
     if (!input || !btn) return;
 
+    // Toggle search help
+    const helpBtn = document.getElementById('searchHelpBtn');
+    const helpPanel = document.getElementById('searchHelp');
+    if (helpBtn && helpPanel) {
+        helpBtn.addEventListener('click', () => {
+            helpPanel.style.display = helpPanel.style.display === 'none' ? '' : 'none';
+        });
+    }
+
     // Search on Enter or button click
     btn.addEventListener('click', () => performSearch(input.value));
     input.addEventListener('keydown', (e) => {
@@ -3842,7 +3851,7 @@ async function performSearch(query) {
                 item.innerHTML = `
                     <div class="d-flex justify-content-between align-items-start">
                         <div>
-                            <span class="badge bg-primary me-1">#${escapeHtml(r.channel_name || '')}</span>
+                            <span class="badge bg-primary me-1">${escapeHtml(r.channel_name || '')}</span>
                             <strong class="small">${r.is_own ? 'You' : escapeHtml(r.sender || '')}</strong>
                         </div>
                         <small class="text-muted">${time}</small>

app/static/js/sw.js

@@ -1,4 +1,4 @@
-const CACHE_NAME = 'mc-webui-v8';
+const CACHE_NAME = 'mc-webui-v9';
 const ASSETS_TO_CACHE = [
     '/',
     '/static/css/style.css',

app/templates/base.html

@@ -417,6 +417,21 @@
                         <button class="btn btn-primary" type="button" id="searchBtn">
                             <i class="bi bi-search"></i>
                         </button>
+                        <button class="btn btn-outline-secondary" type="button" id="searchHelpBtn" title="Search syntax help">
+                            <i class="bi bi-question-circle"></i>
+                        </button>
+                    </div>
+                    <div id="searchHelp" class="alert alert-light small mb-3" style="display:none;">
+                        <strong>Search tips:</strong>
+                        <ul class="mb-1 ps-3">
+                            <li><code>hello world</code> — messages containing both words</li>
+                            <li><code>"hello world"</code> — exact phrase</li>
+                            <li><code>hello OR world</code> — either word</li>
+                            <li><code>hello NOT world</code> — hello but not world</li>
+                            <li><code>hell*</code> — prefix match (hello,hellas...)</li>
+                        </ul>
+                        <div class="text-muted">Special characters (<code>. , - :</code>) should be wrapped in quotes.<br>
+                        <a href="https://www.sqlite.org/fts5.html#full_text_query_syntax" target="_blank" rel="noopener">Full FTS5 syntax reference <i class="bi bi-box-arrow-up-right"></i></a></div>
                     </div>
                     <div id="searchResults">
                         <div class="text-center text-muted py-4">