SEC-API-2: WorkspaceGuard now propagates database errors as 500s instead of returning "access denied". Only Prisma P2025 (record not found) is treated as "user not a member". SEC-API-3: PermissionGuard now propagates database errors as 500s instead of returning null role (which caused permission denied). Only Prisma P2025 is treated as "not a member". This prevents connection timeouts, pool exhaustion, and other infrastructure errors from being misreported to users as authorization failures. Refs #337 Co-Authored-By: Claude Opus 4.5 <[email protected]>