fix(chat): extract SLIDE_ORDER to shared module for server-side import

useSlideNavigation.ts has 'use client' — server API routes can't import
from it. Move SLIDE_ORDER to lib/slide-order.ts (no 'use client') and
re-export from useSlideNavigation for backwards compat.

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

pitch-deck/lib/slide-order.ts

@@ -0,0 +1,26 @@
+import { SlideId } from './types'
+
+export const SLIDE_ORDER: SlideId[] = [
+  'intro-presenter',
+  'cover',
+  'problem',
+  'solution',
+  'product',
+  'how-it-works',
+  'market',
+  'business-model',
+  'traction',
+  'competition',
+  'team',
+  'financials',
+  'the-ask',
+  'ai-qa',
+  'annex-assumptions',
+  'annex-architecture',
+  'annex-gtm',
+  'annex-regulatory',
+  'annex-engineering',
+  'annex-aipipeline',
+]
+
+export const TOTAL_SLIDES = SLIDE_ORDER.length