feat(community): Post.gameName + GameShareBanner-rendering chain

Adds optional `gameName` column to community_posts so game-share posts
can render with the game-banner above the post-content (Snake/Tetris/
Memory/TTT visual indicator).

- prisma/schema.prisma: CommunityPost.gameName String? @map("game_name")
- migration: ALTER TABLE rebreak.community_posts ADD COLUMN game_name
- db/community.ts: createPost() accepts gameName param
- api/community/post.post.ts: extracts gameName from body
- api/community/posts.get.ts: returns gameName, prefers DB over content-parse

Frontend (already in flight on upgrade/sdk-54): PostCard.tsx renders
GameShareBanner when post.category === 'game_share' && post.gameName.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/prisma/migrations/20260509_add_post_game_name/migration.sql

@@ -0,0 +1,3 @@
+-- Migration: add game_name column to community_posts
+-- Generated: 2026-05-09
+ALTER TABLE "rebreak"."community_posts" ADD COLUMN "game_name" TEXT;

backend/prisma/schema.prisma

@@ -160,6 +160,7 @@ model CommunityPost {
     deletedAt     DateTime? @map("deleted_at")
     /// Wann der Post zum ersten Mal gemeldet wurde (queue-Sortierung).
     reportedAt    DateTime? @map("reported_at")
+    gameName      String?  @map("game_name")
     repostOfId    String?  @map("repost_of_id") @db.Uuid
     challengeId   String?  @map("challenge_id") @db.Uuid
     createdAt     DateTime @default(now()) @map("created_at")

backend/server/api/community/post.post.ts

@@ -14,10 +14,11 @@ export default defineEventHandler(async (event) => {
   const user = await requireUser(event);
 
   const body = await readBody(event);
-  const { category, content, imageUrl } = body as {
+  const { category, content, imageUrl, gameName } = body as {
     category: string;
     content: string;
     imageUrl?: string;
+    gameName?: string | null;
   };
 
   if (!content?.trim() || !category) {
@@ -72,7 +73,7 @@ export default defineEventHandler(async (event) => {
     }
   }
 
-  const data = await createPost(user.id, category, content.trim(), imageUrl);
+  const data = await createPost(user.id, category, content.trim(), imageUrl, gameName ?? null);
 
   // Punkte vergeben
   await awardPoints(user.id, "post_created", { post_id: data.id });

backend/server/api/community/posts.get.ts

@@ -64,9 +64,9 @@ export default defineEventHandler(async (event) => {
         : null,
       gameName: (p as any).challengeId
         ? challengeStatuses[(p as any).challengeId]?.gameType ?? null
-        : p.category === "game_share"
+        : (p as any).gameName ?? (p.category === "game_share"
           ? p.content.split("\n")[0] ?? null
-          : null,
+          : null),
       opponentName: (p as any).challengeId
         ? challengeStatuses[(p as any).challengeId]?.opponentName ?? null
         : null,

backend/server/db/community.ts

@@ -256,6 +256,7 @@ export async function createPost(
   category: string,
   content: string,
   imageUrl?: string,
+  gameName?: string | null,
 ) {
   const db = usePrisma();
   return db.communityPost.create({
@@ -264,6 +265,7 @@ export async function createPost(
       category,
       content,
       imageUrl: imageUrl || null,
+      gameName: gameName ?? null,
       isAnonymous: false,
       isModerated: false,
     },