research: add guarded GSAE-E0 Stage-A conformance apparatus

[ndrorchestration]

Summary

Implements the bounded Stage-A conformance apparatus tracked in #6 on top of PR #5's exact contract branch.

This is a stacked research-apparatus PR. Base is design/cross-runtime-contract-v1; source under test remains PR #5 exact head 07a09698ca66e8837d04e6ec05b4de3448eced04.

Added

• isolated experiments/gsae_e0/ research package;
• 28-fixture frozen Stage-A candidate and deterministic loader;
• typed fixture/result/evidence schemas;
• structured-semantic classification for AUTH-01–AUTH-10;
• ACP-native behavior and fail-closed negative probes;
• exact source ancestry + ACP-source-drift verification;
• deterministic result/evidence identities and retry lineage;
• guarded in-memory Stage-A orchestration requiring explicit execution identities;
• synthetic-only runner tests;
• README with explicit evidence ceiling;
• pytest discovery for the research tests and full-history checkout needed for source-binding proof.

Verification

Exact apparatus head: 2548ec7a2072d848360481fcf972270204f8aff8.

Push workflow run 35064353443 completed SUCCESS across Python 3.10–3.14.

Fresh PR-event workflow run 35065405012 also completed SUCCESS on the same exact head across Python 3.10–3.14; representative job reports 126 passed, 0 failed.

Comparison from PR #5 source head to the apparatus head shows no changes under src/agent_control_plane/.

Evidence ceiling

This PR can establish only that the Stage-A apparatus is implemented, deterministic under its tests, source-bound, and ready for review.

It does not establish or authorize:

• a canonical GSAE-E0 Stage-A run;
• contract feasibility or portability;
• DGAF/PDMAL efficacy or authorization;
• production/security certification;
• empirical/scientific N > 0.

Current research state: R2 FROZEN / APPARATUS_READY / EXECUTION NOT AUTHORIZED / NOT RUN / N=0.

Issue #6 is closed as the completed apparatus-build record. PR #7 remains the stacked review surface. R2 freeze acceptance is separate from execution authorization.