Inline dotify adds trailing dot for 57‑char multiples, producing invalid QNAMEs

[Mygod]

The inline dot insertion helper (slipstream_inline_dotify) inserts a dot when the encoded base32 length is a multiple of 57. In slipstream_client.c, the code then appends another dot before the domain suffix, yielding .. in the QNAME (e.g., a 71‑byte payload → base32 length 114 → dotted payload ends with .). SPCDNS treats .. as end‑of‑name, so the domain suffix is dropped and the QNAME is malformed. This makes certain payload sizes fail or bypass the intended suffix check. Consider skipping the trailing dot for exact 57‑char segments.