fix: mark dynamic routes as force-dynamic to prevent static generation errors

Next.js build was failing because routes using headers() were being
statically generated during build time. Added `export const dynamic = 'force-dynamic'`
to:
- /api/player-stats (uses getViewerId which reads headers)
- /api/debug/active-players (uses getViewerId which reads headers)
- /opengraph-image (reads filesystem during render)

Build errors:
- Route /api/player-stats couldn't be rendered statically because it used `headers`
- Route /api/debug/active-players couldn't be rendered statically because it used `headers`
- Error occurred prerendering page "/opengraph-image"

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

apps/web/src/app/api/debug/active-players/route.ts

@@ -4,6 +4,9 @@ import { getActivePlayers } from '@/lib/arcade/player-manager'
 import { db, schema } from '@/db'
 import { eq } from 'drizzle-orm'
 
+// Force dynamic rendering - this route uses headers()
+export const dynamic = 'force-dynamic'
+
 /**
  * GET /api/debug/active-players
  * Debug endpoint to check active players for current user

apps/web/src/app/api/player-stats/route.ts

@@ -7,6 +7,9 @@ import { players } from '@/db/schema/players'
 import type { GetAllPlayerStatsResponse, PlayerStatsData } from '@/lib/arcade/stats/types'
 import { getViewerId } from '@/lib/viewer'
 
+// Force dynamic rendering - this route uses headers()
+export const dynamic = 'force-dynamic'
+
 /**
  * GET /api/player-stats
  *

apps/web/src/app/opengraph-image.tsx

@@ -4,6 +4,7 @@ import { join } from 'path'
 
 // Route segment config
 export const runtime = 'nodejs'
+export const dynamic = 'force-dynamic'
 
 // Image metadata
 export const alt = 'Abaci.One - Interactive Soroban Learning Platform'