Use uri for the like and bookmark permalinks

`uri` is the attribute every other postable model uses for its absolute
permalink on this site. Add it to Like, which had none, and rename
Bookmark's `local_uri` to match. `url` stays as the thing being liked or
bookmarked.

Refs #148

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/Unit/LikesTest.php

@@ -13,6 +13,14 @@ class LikesTest extends TestCase
 {
     use RefreshDatabase;
 
+    #[Test]
+    public function like_uri_attribute_returns_our_permalink(): void
+    {
+        $like = Like::factory()->create();
+
+        $this->assertEquals(config('app.url').'/likes/'.$like->id, $like->uri);
+    }
+
     #[Test]
     public function we_can_set_the_author_url(): void
     {