S9F3/F5 are covered by test_s9_fallback (router path); S9F9/F11 by
test_hsms_timers (timer/over-length). This commit adds S9F7 wire-level
tests for the third path — a primary whose body fails secs2::decode.
Three new cases:
- hand-built primary with truncated <B> body provokes S9F7
carrying the original 10-byte MHEAD (sys + stream + function)
- emission is non-fatal: the next well-formed primary still routes
to the registered handler
- data-while-NOT-SELECTED still echoes Reject(EntityNotSelected)
(sanity copy of the test_hsms_connection case so the "what does
the equipment say when a peer sends garbage" family lives together)
Closes#6 in the test-gap backlog.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
