feat: v0.2.0 — API REST, TTS support, documentazione completa e UI mobile-first

✨ Nuove funzionalità:
- Nuovo endpoint API REST /api/v1/query (GET+POST) per consumo programmatico
- Campo speakable_text ottimizzato per sintesi vocale (Alexa, Google Home)
- Funzione strip_markdown() per conversione Markdown → plain text TTS
- Supporto CORS per accesso cross-origin
- UI responsive mobile-first con micro-interazioni e stati
- Nuovo pulsante 'Nuova ricerca' e metadata bar

📚 Documentazione completa:
- docs/ARCHITECTURE.md — architettura di sistema, stack, componenti
- docs/FLOW.md — diagrammi Mermaid della pipeline e flussi
- docs/API.md — documentazione endpoint REST con esempi curl
- docs/WIKI.md — FAQ, glossario, roadmap
- docs/DEPLOYMENT.md — guida deployment (Gunicorn, Nginx, Docker, systemd)
- docs/CONTRIBUTING.md — guida alla contribuzione

🔧 Migliorie tecniche:
- Pipeline di ricerca condivisa in _run_search_pipeline()
- Gestione errori Gemini migliorata con _clean_error()
- Sanitizzazione HTML con allowlist per prevenzione XSS
- .env.example completo con commenti

🧪 Test: 109/109 passati

static/app.js

@@ -1,5 +1,6 @@
 /**
  * Sibilla — Frontend search interface
+ * Mobile-friendly, smooth UX
  */
 
 document.addEventListener('DOMContentLoaded', () => {
@@ -10,19 +11,34 @@ document.addEventListener('DOMContentLoaded', () => {
     const loading = document.getElementById('loading');
     const answerDiv = document.getElementById('answer');
     const sourcesDiv = document.getElementById('sources');
+    const metaBar = document.getElementById('meta-bar');
+    const newSearchBtn = document.getElementById('new-search-btn');
+
+    const btnText = submitBtn.querySelector('span').textContent;
+    let isSearching = false;
 
     form.addEventListener('submit', async (e) => {
         e.preventDefault();
 
+        if (isSearching) return;
+
         const query = queryInput.value.trim();
         if (!query) return;
 
-        // Show response area + loading
+        // Reset and show UI
+        isSearching = true;
         responseArea.style.display = 'block';
         loading.style.display = 'flex';
         answerDiv.innerHTML = '';
         sourcesDiv.innerHTML = '';
+        metaBar.innerHTML = '';
+        metaBar.style.display = 'none';
+        newSearchBtn.classList.remove('visible');
         submitBtn.disabled = true;
+        submitBtn.querySelector('span').textContent = 'Consultando...';
+
+        // Scroll to loading indicator on mobile
+        loading.scrollIntoView({ behavior: 'smooth', block: 'start' });
 
         try {
             const res = await fetch('/api/ask', {
@@ -38,29 +54,63 @@ document.addEventListener('DOMContentLoaded', () => {
 
             const data = await res.json();
 
-            // Render answer as Markdown
-            answerDiv.innerHTML = renderMarkdown(data.answer);
+            // Render answer — prefer server-rendered HTML, fall back to client-side markdown
+            if (data.html_answer) {
+                answerDiv.innerHTML = data.html_answer;
+            } else {
+                answerDiv.innerHTML = renderMarkdown(data.answer);
+            }
+
+            // Render metadata bar
+            if (data.search_engine || data.tokens_used) {
+                let metaHtml = '';
+                if (data.search_engine && data.search_engine !== 'none') {
+                    metaHtml += `<span class="meta-badge engine">🔍 ${data.search_engine}</span>`;
+                }
+                if (data.model) {
+                    metaHtml += `<span class="meta-badge">🧠 ${data.model}</span>`;
+                }
+                if (data.tokens_used) {
+                    metaHtml += `<span class="meta-badge">📊 ~${data.tokens_used} token</span>`;
+                }
+                metaBar.innerHTML = metaHtml;
+                metaBar.style.display = 'flex';
+            }
 
             // Render sources
             if (data.sources && data.sources.length > 0) {
                 sourcesDiv.innerHTML = '<h3>📚 Fonti</h3>' +
                     data.sources.map(s =>
                         `<a href="${escapeHtml(s.url)}" target="_blank" rel="noopener" class="source-item">
+                            <span class="source-index">${s.index}</span>
                             <span class="source-title">${escapeHtml(s.title)}</span>
                             <span class="source-url">${escapeHtml(s.url)}</span>
                         </a>`
                     ).join('');
             }
 
+            // Show "new search" button and scroll to results
+            newSearchBtn.classList.add('visible');
+            answerDiv.scrollIntoView({ behavior: 'smooth', block: 'start' });
+
         } catch (err) {
             answerDiv.innerHTML = `<div class="error-box">⚠️ ${escapeHtml(err.message)}</div>`;
+            answerDiv.scrollIntoView({ behavior: 'smooth', block: 'start' });
         } finally {
             loading.style.display = 'none';
             submitBtn.disabled = false;
+            submitBtn.querySelector('span').textContent = btnText;
+            isSearching = false;
         }
     });
 
-    // Allow Ctrl+Enter to submit
+    // "New search" button — scroll back to query input
+    newSearchBtn.addEventListener('click', () => {
+        queryInput.focus();
+        queryInput.scrollIntoView({ behavior: 'smooth', block: 'center' });
+    });
+
+    // Allow Ctrl+Enter or Cmd+Enter to submit
     queryInput.addEventListener('keydown', (e) => {
         if (e.key === 'Enter' && (e.ctrlKey || e.metaKey)) {
             form.dispatchEvent(new Event('submit'));
@@ -69,6 +119,7 @@ document.addEventListener('DOMContentLoaded', () => {
 });
 
 // ── Tiny Markdown renderer ─────────────────────────────────────
+
 function renderMarkdown(text) {
     if (!text) return '';