add content-script and file to manifest

this will be what interacts with a search result page to flag links to slop

manifest.json

@@ -14,5 +14,12 @@
         "scripts": ["scripts/report-slop.js"],
         "persistent": false,
         "type": "module"
+    },
+
+    "content_scripts": [
+        {
+            "matches": ["*://*.duckduckgo.com/*"],
+            "js": ["scripts/hide-slop.js"]
         }
+    ]
 }