Adds docs/ci-cd.md "The jq contract" (1.6 floor, the three divergent constructs,
and the deliberate pin-vs-floor asymmetry with its merge-deadlock reason), plus two
decision records: ci.jq-version-contract and ci.shared-pr-file-enumeration.
ci.script-tests-job stops restating the three jq rules and points at the new record.
Also corrects the script-tests preflight description: it is now two steps (git
presence, then jq VERSION via scripts/jq-preflight.sh --expect 1.6), not one.
A literal NUL byte had crept into the ci-cd.md paragraph describing jq 1.6's NUL
truncation — which git treats as a binary file. Replaced with the literal text.
Decisions-Edit: yes
timothy
63fa81fbb5