fix: add web_accessible_resources for interceptors.js in manifest.json

Without this, Chrome blocks chrome.runtime.getURL('interceptors.js')
in Manifest V3, causing HLS detection to silently fail.

Added regression test to prevent future removal.

__tests__/config_validation.test.mjs

@@ -79,4 +79,24 @@ describe('Config: build integrity', () => {
       throw new Error('No content_scripts entry references content.js');
     }
   });
+
+  it('manifest.json must declare interceptors.js in web_accessible_resources', () => {
+    const manifest = JSON.parse(
+      readFileSync(resolve(root, 'manifest.json'), 'utf8')
+    );
+    const war = manifest.web_accessible_resources;
+    if (!war || !Array.isArray(war)) {
+      throw new Error(
+        'manifest.json has no web_accessible_resources. ' +
+        'interceptors.js needs this for chrome.runtime.getURL() to work.'
+      );
+    }
+    const allResources = war.flatMap(entry => entry.resources || []);
+    if (!allResources.includes('interceptors.js')) {
+      throw new Error(
+        'manifest.json web_accessible_resources must include interceptors.js. ' +
+        'Without it, the browser blocks chrome.runtime.getURL("interceptors.js").'
+      );
+    }
+  });
 });