chore: Add action to headlines and sources

- Added action to headlines.json
- Added action to sources.json

Author: fulleni

lib/src/fixtures/headlines.json

@@ -10,12 +10,22 @@
       "id": "s1a2b3c4-d5e6-f789-0123-456789abcdef",
       "name": "Very Good Ventures Blog",
       "url": "https://vgv.dev/blog",
-      "type": "blog"
+      "type": "blog",
+      "action": {
+        "type": "open_internal_content",
+        "content_id": "s1a2b3c4-d5e6-f789-0123-456789abcdef",
+        "content_type": "source"
+      }
     },
     "category": {
       "id": "c1a2b3c4-d5e6-f789-0123-456789abcdef",
       "name": "Technology",
-      "description": "News about software development and frameworks."
+      "description": "News about software development and frameworks.",
+      "action": {
+        "type": "open_internal_content",
+        "content_id": "c1a2b3c4-d5e6-f789-0123-456789abcdef",
+        "content_type": "category"
+      }
     },
     "action": {
       "type": "open_internal_content",
@@ -34,12 +44,22 @@
       "id": "s2b3c4d5-e6f7-a890-1234-567890abcdef",
       "name": "Flutter Dev",
       "url": "https://flutter.dev",
-      "type": "specializedPublisher"
+      "type": "specializedPublisher",
+      "action": {
+        "type": "open_internal_content",
+        "content_id": "s2b3c4d5-e6f7-a890-1234-567890abcdef",
+        "content_type": "source"
+      }
     },
     "category": {
       "id": "c2b3c4d5-e6f7-a890-1234-567890abcdef",
       "name": "Mobile Development",
-      "description": "Articles related to mobile app development."
+      "description": "Articles related to mobile app development.",
+      "action": {
+        "type": "open_internal_content",
+        "content_id": "c2b3c4d5-e6f7-a890-1234-567890abcdef",
+        "content_type": "category"
+      }
     },
     "action": {
       "type": "open_internal_content",

lib/src/fixtures/sources.json

@@ -52,7 +52,12 @@
       "id": "country-gb",
       "iso_code": "GB",
       "name": "United Kingdom",
-      "flag_url": "https://example.com/flags/gb.png"
+      "flag_url": "https://example.com/flags/gb.png",
+      "action": {
+        "type": "open_internal_content",
+        "content_id": "country-gb",
+        "content_type": "country"
+      }
     },
     "action": {
       "type": "open_internal_content",