Add admin UI + MinIO image uploads

- Admin API: list/edit posts (incl. drafts, raw markdown), moderate comments, subscribers,
  author bio/links, and presigned image upload to MinIO (bucket is public-read for covers).
- Admin UI at /admin: post editor with cover-image upload, comment moderation, subscriber list.
- Public security switched to authenticated-paths so static assets (/images, /data) stay public.

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

@@ -1,56 +0,0 @@
-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();
-    }
-}