Add connection groups with sidebar sections and combo-box editor

Sidebar:
- Profiles are now organised into group-based sections
- Groups appear alphabetically between Favourites/Recent and Ungrouped
- Section key uses 'group:Name' prefix to avoid collisions
- Ungrouped profiles fall into 'Ungrouped' (or 'All Connections' if
  no groups exist)

Profile editor:
- Add Group combo-box field to General section
- Uses HTML datalist backed by distinct group names from all profiles
- Typing a new name creates the group; selecting existing reuses it
- Help text explains the behaviour

Save handler:
- folder field now collected from form and trimmed

The Go model already had a 'folder' field — this change wires it
into the UI end-to-end.

frontend/src/js/profiles.js

@@ -242,10 +242,63 @@ class ProfileEditor {
             this._field('text', 'host', 'Host', profile.host, { placeholder: '192.168.1.1 or example.com', required: true }),
             this._field('number', 'port', 'Port', profile.port, { min: 1, max: 65535, required: true }),
             this._field('text', 'username', 'Username', profile.username, { placeholder: 'root' }),
+            this._renderGroupField(profile),
             this._field('text', 'description', 'Description', profile.description, { placeholder: 'Optional description' }),
         ]);
     }
 
+    /**
+     * Renders a combo-box for the Group field — a text input backed by a
+     * datalist of existing group names. Typing a new name creates a group.
+     * @param {Object} profile
+     * @returns {HTMLElement}
+     * @private
+     */
+    _renderGroupField(profile) {
+        const group = createElement('div', 'form-group');
+        const label = createElement('label', 'form-label', {
+            textContent: 'Group',
+            for: 'field-folder',
+        });
+        group.appendChild(label);
+
+        // Collect distinct group names from all profiles
+        const existingGroups = [...new Set(
+            this.app.state.profiles
+                .map((p) => (p.folder || '').trim())
+                .filter(Boolean)
+        )].sort((a, b) => a.localeCompare(b));
+
+        // Create the datalist so the browser offers autocomplete
+        const listId = 'folder-suggestions';
+        const datalist = document.createElement('datalist');
+        datalist.id = listId;
+        for (const g of existingGroups) {
+            const opt = document.createElement('option');
+            opt.value = g;
+            datalist.appendChild(opt);
+        }
+        group.appendChild(datalist);
+
+        const input = createElement('input', 'form-input', {
+            type: 'text',
+            id: 'field-folder',
+            name: 'folder',
+            value: profile.folder || '',
+            placeholder: 'e.g. Production, Staging, Home Lab',
+        });
+        input.setAttribute('list', listId);
+        input.setAttribute('autocomplete', 'off');
+        group.appendChild(input);
+
+        const hint = createElement('span', 'form-hint', {
+            textContent: 'Choose an existing group or type a new name to create one',
+        });
+        group.appendChild(hint);
+
+        return group;
+    }
+
     /** @private */
     _renderSSHSections(profile) {
         const ssh = profile.ssh || {};
@@ -694,6 +747,7 @@ class ProfileEditor {
         p.port = val('port') || p.port;
         p.username = val('username') || '';
         p.description = val('description') || '';
+        p.folder = (val('folder') || '').trim();
         p.terminalFontFamily = val('terminalFontFamily') || '';
         p.terminalFontSize = val('terminalFontSize') || 14;
         p.terminalScrollback = val('terminalScrollback') || 10000;

frontend/src/js/sidebar.js

@@ -30,6 +30,11 @@ class Sidebar {
 
     /**
      * Full re-render of the sidebar profile list.
+     * Profiles are organised into:
+     *   1. Favourites (if any)
+     *   2. Recent (last 5 connected)
+     *   3. One section per group (sorted alphabetically)
+     *   4. Ungrouped (profiles with no group assigned)
      */
     render() {
         if (!this.el) return;
@@ -40,7 +45,7 @@ class Sidebar {
         // Favourites
         const favourites = profiles.filter((p) => p.favourite);
         if (favourites.length > 0) {
-            this._renderSection('Favourites', 'favourites', favourites);
+            this._renderSection('★ Favourites', 'favourites', favourites);
         }
 
         // Recent
@@ -52,8 +57,32 @@ class Sidebar {
             this._renderSection('Recent', 'recent', recent);
         }
 
-        // All connections
-        this._renderSection('All Connections', 'all', profiles);
+        // ── Group-based sections ─────────────────────────────────────
+        // Collect distinct groups and sort them alphabetically.
+        const groupMap = new Map();
+        const ungrouped = [];
+
+        for (const p of profiles) {
+            const grp = (p.folder || '').trim();
+            if (grp) {
+                if (!groupMap.has(grp)) groupMap.set(grp, []);
+                groupMap.get(grp).push(p);
+            } else {
+                ungrouped.push(p);
+            }
+        }
+
+        // Render each group as its own collapsible section
+        const sortedGroups = [...groupMap.keys()].sort((a, b) => a.localeCompare(b));
+        for (const grp of sortedGroups) {
+            this._renderSection(grp, `group:${grp}`, groupMap.get(grp));
+        }
+
+        // Ungrouped connections
+        if (ungrouped.length > 0) {
+            const label = sortedGroups.length > 0 ? 'Ungrouped' : 'All Connections';
+            this._renderSection(label, 'ungrouped', ungrouped);
+        }
 
         // Empty state
         if (profiles.length === 0) {