detect_content_type() peeked at m_buffer[m_body] to infer JSON vs XML
when no CONTENT_TYPE header was provided. When the TCP header segment
arrives without any body bytes, m_body equals m_position and the peek
reads the null terminator padding byte — not the actual '{' or '[' —
causing JSON requests to be incorrectly classified as XML and fail.
Fix:
- Remove the body peek from detect_content_type(); defer it to after
the full body is confirmed present in event_read().
- Add a m_content_type_set flag to distinguish header-provided type
from auto-detected type.
trim21
b0ef95592b