fix(agent99): frame remote bootstrap input

scripts/reboot-recovery/deploy-agent99-via-windows99-ssh.sh

@@ -320,8 +320,16 @@ compressed = gzip.compress(
     compresslevel=9,
     mtime=0,
 )
+payload = base64.b64encode(compressed).decode("ascii")
+line_width = 65536
+payload_lines = [
+    payload[offset : offset + line_width]
+    for offset in range(0, len(payload), line_width)
+]
+if not payload_lines or len(payload_lines) > 8:
+    raise SystemExit("remote_bootstrap_payload_line_contract_failed")
 output_path.write_text(
-    base64.b64encode(compressed).decode("ascii") + "\n" + sentinel + "\n",
+    "\n".join(payload_lines) + "\n" + sentinel + "\n",
     encoding="ascii",
 )
 PY

scripts/reboot-recovery/tests/test_agent99_remote_atomic_deploy_transport_contract.py

@@ -154,6 +154,10 @@ def test_sender_builds_sha256_envelope_and_streams_it_without_remote_cli_data()
     assert "[Console]::In.ReadLine()" in source
     assert "remote_bootstrap_input_limit_exceeded" in source
     assert "remote_bootstrap_sentinel_missing" in source
+    assert "line_width = 65536" in source
+    assert "len(payload_lines) > 8" in source
+    assert '"\\n".join(payload_lines)' in source
+    assert "remote_bootstrap_payload_line_contract_failed" in source
     assert "$lineCount -gt 8" in source
     assert "$charCount -gt 1048576" in source
     assert '<"${BOOTSTRAP_PAYLOAD_PATH}"' in source