OpportunisticCsiBridge::ingest built CsiReportPayload.n_subcarriers via
`self.amp_accum.len() as u16`, which would silently wrap a count above 65_535.
Replace with `u16::try_from(...).ok()?` (drop-instead-of-truncate). Disclosed
honestly as defense-in-depth on an UNREACHABLE path: ingest already gates
subcarrier_count > MAX_REPORT_SUBCARRIERS (484) at entry and report.validate()
rejects oversized counts downstream, so the cast can never wrap in practice.
Correct-by-construction rather than gate-dependent; no behavior change, no new
test (the gate prevents the input that would exercise it).
Co-Authored-By: claude-flow <ruv@ruv.net>
0b78eb6e03