refactor(core): modularize ASCII logic and add dither/edge detection

package-lock.json

@@ -13,6 +13,7 @@
         "@astrojs/node": "^9.5.2",
         "astro": "^5.17.1",
         "gifuct-js": "^2.1.2",
+        "pngjs": "^7.0.0",
         "typescript": "^5.9.3"
       }
     },
@@ -4387,6 +4388,15 @@
         "url": "https://github.com/sponsors/jonschlinkert"
       }
     },
+    "node_modules/pngjs": {
+      "version": "7.0.0",
+      "resolved": "https://registry.npmjs.org/pngjs/-/pngjs-7.0.0.tgz",
+      "integrity": "sha512-LKWqWJRhstyYo9pGvgor/ivk2w94eSjE3RGVuzLGlr3NmD8bf7RcYGze1mNdEHRP6TRP6rMuDHk5t44hnTRyow==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=14.19.0"
+      }
+    },
     "node_modules/postcss": {
       "version": "8.5.6",
       "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.6.tgz",