fix: resize images to 2550 px (300 DPI) at build time to prevent WSL2 OOM crash

4096×4096 source images decoded simultaneously by Chromium consumed ~3.2 GB,
exhausting WSL2 RAM. Build now uses sharp to downsize to 2550×2550 (8.5 in ×
300 DPI) into output/resized/ before Puppeteer loads them, cutting in-memory
footprint to ~1.25 GB. Also adds all story images (01–12) to the repository.

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

package.json

@@ -24,6 +24,7 @@
     "gray-matter": "^4.0.3",
     "marked": "^12.0.0",
     "nunjucks": "^3.2.4",
-    "puppeteer": "^24.42.0"
+    "puppeteer": "^24.42.0",
+    "sharp": "^0.34.5"
   }
 }