fix: find-similar marks replaceable matches and names excluded types (review M-3, M-7, M-8)

Every match carries replaceable: true only when it is identical and in a
page or post, the scope lit/library-make-global replaces; the description
and the guide say so. An excluded post type is answered like any
unavailable one, by its name (PostGuard::unavailableType()), and the
excluded list takes the Theme Builder types from DiviThemeBuilder::postTypes().

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7

tests/Unit/Integrations/Divi/Library/LibraryFindSimilarAbilityTest.php

@@ -150,14 +150,50 @@ final class LibraryFindSimilarAbilityTest extends TestCase
     {
         Functions\expect('get_posts')->never();
 
-        foreach (['et_pb_layout', 'et_body_layout', 'et_header_layout', 'et_footer_layout', 'et_template'] as $type) {
-            self::assertToolError(
-                self::ability()->execute(['library_id' => 1055, 'post_type' => $type]),
-                'not_found'
-            );
+        foreach (
+            ['et_pb_layout', 'et_body_layout', 'et_header_layout', 'et_footer_layout', 'et_template', 'et_theme_builder']
+            as $type
+        ) {
+            $refused = self::ability()->execute(['library_id' => 1055, 'post_type' => $type]);
+            self::assertToolError($refused, 'not_found');
+            // Review M-7: named like any unavailable type, never as "".
+            self::assertSame(sprintf('Inhaltstyp "%s" ist nicht verfügbar.', $type), self::clientError($refused)['message']);
         }
     }
 
+    /**
+     * Review M-8: lit/library-make-global replaces only pages and posts – every match says whether it can be
+     * replaced there (identical and of such a type).
+     */
+    public function testMatchesSayWhetherMakeGlobalCanReplaceThem(): void
+    {
+        $project = get_post(8);
+        $project = new WP_Post(['ID' => 10, 'post_type' => 'project', 'post_status' => 'publish', 'post_title' => 'Projekt',
+            'post_content' => $project->post_content]);
+        LibraryFixtures::given(array_merge([get_post(8), $project], array_map(
+            static fn (int $id): WP_Post => LibraryFixtures::item($id),
+            array_keys(LibraryFixtures::ITEMS)
+        )));
+        Functions\when('get_post_type_object')->justReturn((object) ['cap' => (object) [
+            'edit_posts' => 'edit_posts',
+            'edit_others_posts' => 'edit_others_posts',
+        ]]);
+        // The query is mocked: it stands for a scan over several Divi-enabled types.
+        Functions\when('get_posts')->justReturn([8, 10]);
+
+        $result = self::ability()->execute(['library_id' => 1055, 'post_type' => 'page']);
+
+        $found = array_map(
+            static fn (array $m): string => sprintf('%d %s %s %s', $m['post_id'], $m['id'], $m['match'], json_encode($m['replaceable'])),
+            $result['matches']
+        );
+        self::assertSame(
+            ['8 s0 structure false', '8 s1 identical true', '10 s0 structure false', '10 s1 identical false'],
+            $found
+        );
+        self::assertStringContainsString('replaceable', self::ability()->description());
+    }
+
     /** With the library group hidden the library entry is answered like a missing ID (P9/P12). */
     public function testAHiddenLibraryAnswersLikeAMissingEntry(): void
     {