[acamarata]

Pin the lock polling delay and cap under a held local file lock, and the CIOptions capacity around OpenSSH 8.5 (8.4/8.5/8.6). Remove the four arithmetic exemptions and refresh the moved scan loop equivalent entry while preserving its justification. Production code is unchanged.

Validation:

• go test -mod=vendor -count=1 ./remote passed in sdk/go.
• go vet -mod=vendor ./remote passed.
• bash scripts/ci/sdk-remote-mutation.sh exited 0: 487 judged, 478 killed, 3 equivalent survivors, 1 allowlisted uncovered initializer, 5 timeouts (limit 8). The gate uses its configured module mode; direct test and vet used a temporary SDK vendor tree, removed after validation.

Mutation output:

KILLED ARITHMETIC_BASE at knownhosts_check.go:285:13
KILLED ARITHMETIC_BASE at knownhosts_check.go:298:27
KILLED ARITHMETIC_BASE at options.go:115:43
KILLED ARITHMETIC_BASE at options.go:115:28
LIVED CONDITIONALS_BOUNDARY at scan.go:140:16
LIVED CONDITIONALS_BOUNDARY at ssh_allow.go:49:15
LIVED CONDITIONALS_BOUNDARY at ssh_allow.go:114:51