nx_tls13_read_record_from_fd_loopback_test.nx

nx_tls13_read_record_from_fd_loopback_test.nx -- REAL happy- path KAT for nx_tls13_read_record_from_fd over real TCP loopback. The existing nx_tls13_read_record_from_fd_test.nx preamble explicitly documents that sys_pipe2 is unreliable in qemu so the original test only exercises bounds-check + read-failure paths. That left the primitive's HAPPY PATH (read a real 5-byte TLS record header + body from a real bidirectional socket) UNVERIFIED. This file closes that gap using the same fork+child socket loopback pattern as nx_https_loopback_test (which has been verified to work in qemu-riscv64-static), exercising ONLY the record-reader primitive in isolation. Test shape: 1. parent: socket + bind + listen on loopback port 2. fork 3. child: socket + connect; build a real TLS record bytes (type=22 handshake, version 0x0303, payload "ABCDE"); sys_write the 10-byte record + close. 4. parent: accept; call nx_tls13_read_record_from_fd(accepted_fd, out_buf, out_cap); verify (a) return value == 10 (5 header + 5 payload) (b) header bytes are correct (0x16 0x03 0x03 0x00 0x05) (c) payload bytes are "ABCDE" 5. parent waits for child + returns child's exit code OR a verdict-specific code if anything mismatched expect_exit: 0 license_tier: ORIGINAL