selected window: declare 1.3-parity, not 1.3, until a completeness proof exists (1.6.1) - #401

…EN-115)

…(EN-115)

Update docs/pages/report-schema.md, docs/pages/public-contract.md,
docker/README.md and README.md so the image declares selected-window
contract revision 1.3-parity (["1.3-parity"] on a supported runtime and []
otherwise), covering value ownership through strategy_value_invalid,
engine_command_value_invalid, report_result_invalid and
report_post_execution_failed, value parity with the 1.4.0 reference on
tested cases, and no completeness claim. Add the 1.6.1 — Unreleased
entry to CHANGELOG.md (EN-115: no completeness proof). VERSION stays
untouched.

Replaces the 1.3 capability sentences introduced by 868aa65 and
517a1b4 (following 47184e5):
- docs/pages/report-schema.md (868aa65): "The engine/codegen 1.6.0 image
  declares selected-window contract revision 1.3, meaning complete value
  ownership with strategy_value_invalid, engine_command_value_invalid,
  report_result_invalid and report_post_execution_failed." and "The
  --capabilities-json probe's capabilities.selected_window_contract_revisions
  is ["1.3"] for a supported runtime and [] otherwise."
- docs/pages/public-contract.md (517a1b4, 868aa65): "It declares
  selected-window contract revision 1.3 (["1.3"] under
  capabilities.selected_window_contract_revisions when the runtime supports
  selected windows and [] otherwise) and extends typed failures across
  source value admission (strategy_value_invalid), derived execution and
  settlement arithmetic (engine_command_value_invalid), non-finite canonical
  trade or summary doubles (report_result_invalid) and post-boundary
  serialization faults (report_post_execution_failed), without changing C
  layouts or PF_ABI_VERSION 4."
- README.md (517a1b4, 868aa65): "The release notes cover selected-window
  contract revision 1.3, typed failures across source values, engine
  arithmetic and report production, finite trade and summary doubles, and the
  documentation, test, CI and benchmark updates since 1.5.0.", "The
  engine/codegen 1.6.0 image advertises selected-window contract revision
  1.3 through docker/run_json.py --capabilities-json: value ownership through
  strategy_value_invalid, engine_command_value_invalid,
  report_result_invalid and report_post_execution_failed.",
  "capabilities.selected_window_contract_revisions is ["1.3"] when the runtime
  supports selected windows and [] otherwise; see the capability table and
  report schema." and the v1.6.0 Releases bullet ("selected-window contract
  revision 1.3").
- docker/README.md (517a1b4, 868aa65): "The engine/codegen 1.6.0 image's
  run_json.py --so <strategy.so> --capabilities-json probe declares revision
  1.3, covering value ownership through strategy_value_invalid,
  engine_command_value_invalid, report_result_invalid and
  report_post_execution_failed." and the selected_window_contract_revisions
  table row.

Update the 1.6.1 selected-window documentation added in 17087c5:
- CHANGELOG.md: say 'as 1.5.0 declared' and note that a build declaring 1.3-parity cannot be promoted to a stable app pin (pinned only as a prerelease 1.6.1-rc.N, and only a completeness proof EN-115 allows '1.3' again).
- README.md, docker/README.md, docs/pages/report-schema.md, docs/pages/public-contract.md: qualify the 1.3-parity declaration as from 1.6.1 (unreleased) and replace 'covering value ownership through' with 'emits the four typed codes'.
- README.md: restore the v1.6.0 Releases bullet's shipped-tag opening and note that 1.6.0 declared contract revision 1.3; corrected to 1.3-parity in 1.6.1.

Resolve docs/pages/report-schema.md: keep #400's fact that the published
1.6.0 image declares 1.3, and this branch's 1.6.1 1.3-parity declaration;
drop the "covering value ownership" wording the #401 review flagged.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>