feat: 'Show CLI sessions' toggle in Settings (#61)

Adds a server-side boolean setting (default: false) that controls whether
CLI sessions from state.db appear in the sidebar. Off by default so the
sidebar is clean until the user explicitly opts in.

- api/config.py: add show_cli_sessions to _SETTINGS_DEFAULTS and _SETTINGS_BOOL_KEYS
- api/routes.py: gate get_cli_sessions() call on the setting at request time
- static/index.html: checkbox in settings panel with description
- static/panels.js: load/save checkbox, refresh session list on save
- static/boot.js: load on startup alongside send_key and show_token_usage

Co-authored-by: Nathan Esquenazi <nesquena@gmail.com>

static/index.html

@@ -331,6 +331,13 @@
         </label>
         <div style="font-size:11px;color:var(--muted);margin-top:4px">Displays input/output token count below each assistant reply. Also toggled with <code>/usage</code>.</div>
       </div>
+      <div class="settings-field">
+        <label style="display:flex;align-items:center;gap:8px;cursor:pointer">
+          <input type="checkbox" id="settingsShowCliSessions" style="width:15px;height:15px;accent-color:var(--accent)">
+          Show CLI sessions in sidebar
+        </label>
+        <div style="font-size:11px;color:var(--muted);margin-top:4px">Merges sessions from the Hermes CLI (state.db) into the session list. Click a CLI session to import it and continue the conversation.</div>
+      </div>
       <div class="settings-field" style="border-top:1px solid var(--border);padding-top:12px;margin-top:8px">
         <label for="settingsPassword">Access Password</label>
         <div style="font-size:11px;color:var(--muted);margin-bottom:6px">Enter a new password to set or change it. Leave blank to keep current setting.</div>