Custom RTMP saved accounts, CUSTOM destination prepare, debug logging

- Add POST /providers/accounts/custom-rtmp endpoint for saved RTMP servers
- Encrypt rtmpUrl/streamKey in accessTokenEnc/refreshTokenEnc fields
- Decrypt and return rtmpUrl/streamKey in GET /providers/accounts for CUSTOM_RTMP
- Skip token revocation on DELETE for CUSTOM_RTMP accounts
- Decrypt CUSTOM_RTMP credentials into CUSTOM destinations on plan create/update
- Handle CUSTOM destinations in prepare lifecycle (already READY, skip provider auth)
- Add debug logging for plan operations and user upsert

src/routes/auth/meta.ts

@@ -57,6 +57,8 @@ const metaAuthRoutes: FastifyPluginAsync = async (fastify) => {
     }
 
     // Upsert user
+    const existingUser = await fastify.prisma.user.findUnique({ where: { metaId } });
+    request.log.info({ metaId, userId: existingUser?.id, isNew: !existingUser }, 'User upsert');
     const user = await fastify.prisma.user.upsert({
       where: { metaId },
       update: { displayName },