feat(pitch-deck): add AI Presenter mode with LiteLLM migration and FAQ system

- Migrate chat API from Ollama to LiteLLM (OpenAI-compatible SSE)
- Add 15-min presenter storyline with bilingual scripts for all 20 slides
- Add FAQ system (30 entries) with keyword matching for instant answers
- Add IntroPresenterSlide with avatar placeholder and start button
- Add PresenterOverlay (progress bar, subtitle text, play/pause/stop)
- Add AvatarPlaceholder with pulse animation during speaking
- Add usePresenterMode hook (state machine: idle→presenting→paused→answering→resuming)
- Add 'P' keyboard shortcut to toggle presenter mode
- Support [GOTO:slide-id] markers in chat responses
- Dynamic slide count (was hardcoded 13, now from SLIDE_ORDER)
- TTS stub prepared for future Piper integration

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

pitch-deck/lib/presenter/faq-matcher.ts

@@ -0,0 +1,72 @@
+import { Language } from '../types'
+import { FAQEntry } from './types'
+import { PRESENTER_FAQ } from './presenter-faq'
+
+/**
+ * Match a user query against pre-cached FAQ entries.
+ * Returns the best match if score exceeds threshold, or null for LLM fallback.
+ */
+export function matchFAQ(query: string, lang: Language): FAQEntry | null {
+  const normalized = query.toLowerCase().trim()
+  const queryWords = normalized.split(/\s+/)
+
+  let bestMatch: FAQEntry | null = null
+  let bestScore = 0
+
+  for (const entry of PRESENTER_FAQ) {
+    let score = 0
+
+    // Check keyword matches
+    for (const keyword of entry.keywords) {
+      const kwLower = keyword.toLowerCase()
+      if (kwLower.includes(' ')) {
+        // Multi-word keyword: check if phrase appears in query
+        if (normalized.includes(kwLower)) {
+          score += 3 * entry.priority / 10
+        }
+      } else {
+        // Single keyword: check word-level match
+        if (queryWords.some(w => w === kwLower || w.startsWith(kwLower) || kwLower.startsWith(w))) {
+          score += 1
+        }
+        // Also check if keyword appears anywhere in query (partial match)
+        if (normalized.includes(kwLower)) {
+          score += 0.5
+        }
+      }
+    }
+
+    // Check if query matches the question text closely
+    const questionText = lang === 'de' ? entry.question_de : entry.question_en
+    const questionWords = questionText.toLowerCase().split(/\s+/)
+    const overlapCount = queryWords.filter(w =>
+      w.length > 2 && questionWords.some(qw => qw.includes(w) || w.includes(qw))
+    ).length
+    if (overlapCount >= 2) {
+      score += overlapCount * 0.5
+    }
+
+    // Weight by priority
+    score *= (entry.priority / 10)
+
+    if (score > bestScore) {
+      bestScore = score
+      bestMatch = entry
+    }
+  }
+
+  // Threshold: need meaningful match to avoid false positives
+  // Require at least 2 keyword hits or strong phrase match
+  if (bestScore < 1.5) {
+    return null
+  }
+
+  return bestMatch
+}
+
+/**
+ * Get FAQ answer text in the requested language
+ */
+export function getFAQAnswer(entry: FAQEntry, lang: Language): string {
+  return lang === 'de' ? entry.answer_de : entry.answer_en
+}