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/hooks/useSlideNavigation.ts

@@ -3,7 +3,8 @@
 import { useState, useCallback } from 'react'
 import { SlideId } from '../types'
 
-const SLIDE_ORDER: SlideId[] = [
+export const SLIDE_ORDER: SlideId[] = [
+  'intro-presenter',
   'cover',
   'problem',
   'solution',