i18n: style the settings select + add a topbar lang toggle

Two issues addressed:

1. The /settings language <select> was unstyled — .settings-select and
   .settings-status classes didn't exist, so the dropdown rendered
   with full native browser chrome and clashed visually with the rest
   of the panel. Added a terminal-aesthetic select: transparent
   background, 1px var(--border), custom chevron via crossed
   linear-gradients, accent border on focus/hover. Disabled options
   (ES/FR/DE 'coming soon') render in --dim.

2. Added a compact EN | IT pill in the topbar next to the theme
   toggle, mirroring the .tone-toggle visual rhythm. Shown only when
   a user is signed in (admins skipped). Optimistic UI: clicking
   flips the pill immediately, PATCHes /api/settings/language, and
   reverts on failure. On /log specifically the page reloads so the
   user sees the localized version of the strategic log right away.

The /settings dropdown still surfaces all five languages (with ES/FR/DE
disabled) for visibility; the topbar pill keeps to the two active
languages to stay compact.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/static/css/cassandra.css

@@ -136,6 +136,35 @@ a:hover { text-decoration: underline; }
   color: var(--bg);
 }
 
+/* Language toggle in the topbar — same visual rhythm as the tone
+ * toggle so the two controls read as a pair. Only EN and IT are
+ * visible here; the WIP languages (ES/FR/DE) live in /settings. */
+.lang-toggle {
+  display: inline-flex;
+  border: 1px solid var(--border);
+  font-family: var(--font-mono);
+  font-size: 10.5px;
+  letter-spacing: 0.06em;
+  text-transform: uppercase;
+}
+.lang-toggle button {
+  background: transparent;
+  color: var(--muted);
+  border: 0;
+  padding: 4px 8px;
+  cursor: pointer;
+  font: inherit;
+  letter-spacing: inherit;
+  text-transform: inherit;
+}
+.lang-toggle button + button { border-left: 1px solid var(--border); }
+.lang-toggle button:hover { color: var(--accent); }
+.lang-toggle[data-lang="en"] button[data-value="en"],
+.lang-toggle[data-lang="it"] button[data-value="it"] {
+  background: var(--accent);
+  color: var(--bg);
+}
+
 .app-main {
   padding: 14px;
   display: grid;
@@ -1020,6 +1049,46 @@ details[open] .pf-analysis__head-left::before { content: "▾ "; }
   margin-left: 8px;
 }
 
+/* Terminal-aesthetic <select> used in the Settings page. Native
+ * browser chrome stripped; we render a small chevron via crossed
+ * linear-gradients so the control matches the rest of the panel. */
+.settings-select {
+  appearance: none;
+  -webkit-appearance: none;
+  -moz-appearance: none;
+  background: transparent;
+  border: 1px solid var(--border);
+  color: var(--text);
+  padding: 4px 28px 4px 8px;
+  font-family: var(--font-mono);
+  font-size: 12px;
+  border-radius: 2px;
+  cursor: pointer;
+  background-image:
+    linear-gradient(45deg, transparent 50%, var(--dim) 50%),
+    linear-gradient(-45deg, transparent 50%, var(--dim) 50%);
+  background-position: calc(100% - 13px) 50%, calc(100% - 9px) 50%;
+  background-size: 5px 5px, 5px 5px;
+  background-repeat: no-repeat;
+  transition: border-color 120ms ease-out, color 120ms ease-out;
+}
+.settings-select:hover,
+.settings-select:focus {
+  outline: none;
+  border-color: var(--accent);
+  color: var(--text);
+}
+.settings-select option { color: var(--text); background: var(--surface); }
+.settings-select option:disabled { color: var(--dim); }
+
+.settings-status {
+  font-family: var(--font-mono);
+  font-size: 11px;
+  color: var(--muted);
+  letter-spacing: 0.04em;
+}
+.settings-status:empty { display: none; }
+
 /* Sections are <details> elements — collapsed by default to keep the
    settings page scannable. Click the summary to expand. */
 .settings-section {

app/templates/base.html

@@ -134,6 +134,34 @@
         if (el && window.htmx) window.htmx.trigger(el, 'tone-changed');
       });
     };
+
+    window.cassandraSetLang = async function (newLang) {
+      var pill = document.getElementById('lang-toggle');
+      if (!pill) return;
+      var prev = pill.dataset.lang;
+      if (prev === newLang) return;
+      // Optimistic update — flip the pill immediately so the click feels
+      // responsive. Revert on PATCH failure.
+      pill.dataset.lang = newLang;
+      try {
+        var r = await fetch('/api/settings/language', {
+          method: 'PATCH',
+          headers: {'Content-Type': 'application/json'},
+          credentials: 'same-origin',
+          body: JSON.stringify({lang: newLang}),
+        });
+        if (!r.ok) throw new Error('HTTP ' + r.status);
+        // Reload localized panels so the user immediately sees content
+        // in the new language (strategic log, dashboard header, etc.).
+        if (window.location.pathname === '/log' ||
+            window.location.pathname.startsWith('/log/')) {
+          window.location.reload();
+        }
+      } catch (e) {
+        pill.dataset.lang = prev;
+        console.warn('language switch failed:', e);
+      }
+    };
   </script>
   <script>
     // Render any <time datetime="..."> in the browser's local timezone.
@@ -180,6 +208,16 @@
         <span class="theme-toggle__label"></span>
       </button>
       {% set cu = request.state.current_user if request.state and request.state.current_user is defined else None %}
+      {% if cu and cu.user %}
+      <div id="lang-toggle" class="lang-toggle" data-lang="{{ cu.user.lang or 'en' }}"
+           role="group" aria-label="AI output language"
+           title="Language the AI uses for the log, digest and portfolio commentary">
+        <button type="button" data-value="en"
+                onclick="cassandraSetLang('en')">EN</button>
+        <button type="button" data-value="it"
+                onclick="cassandraSetLang('it')">IT</button>
+      </div>
+      {% endif %}
       {% if cu and (cu.user or cu.is_admin) %}
       <div class="user-menu">
         <button type="button" id="user-menu-toggle" class="user-chip"