OpenCode 2 host-schema contract deletion guard
affected subcase: read/T2/invalid_arguments

Positive control before mutation
$ node tests/docker/opencode2/contract/probe/verify-host-schema-contract.mjs read/T2/invalid_arguments
PASS read/T2/invalid_arguments host_schema_rejection 0.0.0-beta-19234 oc2-host-schema-20260909-01
[exit 0]

Deletion mutation (performed only after `git add -A` captured the live working state)
$ echo 'NON-VACUITY BREAK: delete host-schema-rejection.json'
NON-VACUITY BREAK: delete host-schema-rejection.json
$ rm tests/docker/opencode2/contract/host-schema-rejection.json
$ git diff --stat
 .../opencode2/contract/host-schema-rejection.json  | 55 ----------------------
 1 file changed, 55 deletions(-)
$ node tests/docker/opencode2/contract/probe/verify-host-schema-contract.mjs read/T2/invalid_arguments
FAIL read/T2/invalid_arguments contract_uncaptured:host_schema_rejection
[exit 1]

Transcript-backed restoration positive control
$ git checkout -- tests/docker/opencode2/contract/host-schema-rejection.json
$ touch tests/docker/opencode2/contract/host-schema-rejection.json
$ git diff --stat
[no output]
$ node tests/docker/opencode2/contract/probe/verify-host-schema-contract.mjs read/T2/invalid_arguments
PASS read/T2/invalid_arguments host_schema_rejection 0.0.0-beta-19234 oc2-host-schema-20260909-01
[exit 0]
