Rewrite as a Spring Boot app on the Bennett platform

Restores the real backend lost with Supabase (posts, authors, comments, subscriptions, admin) in
Postgres, seeds the existing markdown posts, and rebuilds the site as a Vite/React SPA served by
Spring — keeping the original styling (serif + tan accent) and content.

src/test/java/net/reformedwitness/cog/ConfessionsApplicationTests.java

@@ -0,0 +1,56 @@
+package net.reformedwitness.cog;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
+import org.testcontainers.containers.PostgreSQLContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+
+import net.reformedwitness.cog.repo.AuthorRepository;
+import net.reformedwitness.cog.repo.PostRepository;
+
+/**
+ * Full-context test against a real Postgres: proves the Flyway schema, the JPA mappings, and the markdown
+ * seeding (front-matter parsing + HTML rendering) all work end to end.
+ */
+@SpringBootTest(properties = {
+        "platform.storage.access-key=test",
+        "platform.storage.secret-key=test"
+})
+@Testcontainers
+class ConfessionsApplicationTests {
+
+    @Container
+    @ServiceConnection
+    static PostgreSQLContainer<?> postgres =
+            new PostgreSQLContainer<>(DockerImageName.parse("postgres:18-alpine"));
+
+    @Autowired
+    PostRepository posts;
+
+    @Autowired
+    AuthorRepository authors;
+
+    @Test
+    void seedsPostsAndAuthorsFromBundledMarkdown() {
+        assertThat(posts.findByPublishedTrueOrderByPublishedOnDescIdDesc()).isNotEmpty();
+        assertThat(authors.findAllByOrderByNameAsc()).isNotEmpty();
+
+        var fourfold = posts.findBySlug("fourfold");
+        assertThat(fourfold).isPresent();
+        assertThat(fourfold.get().getTitle()).isNotBlank();
+        assertThat(fourfold.get().getAuthor()).isNotBlank();
+        assertThat(fourfold.get().getTags()).isNotEmpty();
+        assertThat(fourfold.get().getContentHtml()).contains("<p>");
+    }
+
+    @Test
+    void tagCountsAreAggregated() {
+        assertThat(posts.tagCounts()).isNotEmpty();
+    }
+}