feat(post-overview): add excludeTag functionality for filtering posts

- Introduced `excludeTag` property in PostOverviewBlockData interface to allow exclusion of specific tag slugs.
- Implemented `excludePostsByTagSlugs` function to filter out posts containing specified tag slugs.
- Updated `resolvePostOverviewBlocks` function to utilize the new exclusion logic, enhancing post filtering capabilities.

src/lib/block-types.ts

@@ -182,6 +182,8 @@ export interface PostOverviewBlockData {
   posts?: unknown[];
   /** Tag-Slugs, nach denen gefiltert wird (nur bei allPosts true). */
   filterByTag?: string[];
+  /** Tag-Slugs, die ausgeschlossen werden (optional, nach filterByTag angewendet). */
+  excludeTag?: string[];
   /** Max. Anzahl Einträge. */
   numberItems?: number;
   /** "list" | "cards". */

src/lib/blog-utils.ts

@@ -164,6 +164,21 @@ export function filterPostsByTagSlugs(
   });
 }
 
+/** Filtert Posts: entfernt solche, die mindestens einen der Tag-Slugs haben. */
+export function excludePostsByTagSlugs(
+  posts: PostEntry[],
+  tagSlugs: string[],
+): PostEntry[] {
+  if (!tagSlugs?.length) return posts;
+  return posts.filter((p) => {
+    const tags = p.postTag ?? [];
+    return !tags.some((t) => {
+      const slug = typeof t === "string" ? t : (t as { _slug?: string })?._slug;
+      return tagSlugs.includes(slug ?? "");
+    });
+  });
+}
+
 export function getTotalPages(count: number, perPage: number): number {
   return Math.max(1, Math.ceil(count / perPage));
 }
@@ -347,6 +362,7 @@ function isPostOverviewBlock(item: unknown): item is {
   allPosts?: boolean;
   posts?: unknown[];
   filterByTag?: unknown[];
+  excludeTag?: unknown[];
   numberItems?: number;
   postsResolved?: unknown[];
 } {
@@ -389,6 +405,16 @@ export async function resolvePostOverviewBlocks(
             )
             .filter(Boolean)
         : [];
+      const rawExclude = item.excludeTag ?? [];
+      const excludeSlugs = Array.isArray(rawExclude)
+        ? rawExclude
+            .map((t) =>
+              typeof t === "string"
+                ? t
+                : ((t as { _slug?: string })?._slug ?? ""),
+            )
+            .filter(Boolean)
+        : [];
       const hasExplicitPosts = Array.isArray(item.posts) && item.posts.length > 0;
       const useAllPosts = item.allPosts || (tagSlugs.length > 0 && !hasExplicitPosts);
       if (useAllPosts) {
@@ -400,6 +426,7 @@ export async function resolvePostOverviewBlocks(
           });
         let list = filterHiddenPosts(sortPostsByDate(allPosts));
         if (tagSlugs.length) list = filterPostsByTagSlugs(list, tagSlugs);
+        if (excludeSlugs.length) list = excludePostsByTagSlugs(list, excludeSlugs);
         const limit =
           typeof item.numberItems === "number" ? item.numberItems : 9999;
         item.postsResolved = list.slice(0, limit);