CLI verification overhaul: add submission verify, auto-verifier in measure; remove validate; aggregate robustness; Nix devshell improvements

[Unisay]

Summary

• Add new cape submission verify wrapper: runs CEK correctness (with scenario/submission verifier when available) and validates schemas. Supports --all, PATH, --verbose, --no-color.
• Remove legacy submission validate command; unify validation under verify as per CLI boundary guidance.
• Measure wrapper improvements: infer scenario from submission path and pass verifier automatically when present; simplify help to reflect stable flags.
• Aggregate robustness: tolerate missing/placeholder fields in metrics/metadata and respect externally provided PROJECT_ROOT (used by tests); avoid pipefail breakage.
• Nix devshell: prefer repo-local scripts/cape.sh inside the shell wrapper; fix measure tool exposure via haskell-nix attr (hsPkgs.measure.components.exes.measure).
• Docs & scenarios: add scenario verifiers for fibonacci and factorial; refresh scenario docs and schemas README; update copilot instructions.
• Measure tool scaffolding: add measure.cabal, fix cabal.project index-state syntax, and include App/Compile.hs, App/Verify.hs, GenerateVerifiers.hs skeleton.
• Test suite & fixtures: add scenario fixtures (returns-42, returns-unit) and update test.sh groups; ensure sandbox overlays and cleanup; increase timeouts where needed.
• Reports & timestamps: refresh generated HTML reports and fixture timestamps to reflect recent measurements.

Rationale

• Aligns with project CLI boundaries: wrapper is repo-aware (verify, measure), core measure remains submission-agnostic.
• Eliminates brittle parsing and permission pitfalls; ensures local iteration uses repo scripts.
• Improves determinism and reproducibility in tests via sandboxed fixtures and auto-verifier behavior.

Breaking/Behavioral changes

• cape submission validate removed in favor of cape submission verify.
• cape submission measure wrapper no longer exposes -i/-o single-file mode; only PATH and --all (as documented). Low-level measure binary still supports -i/-o.

Testing

• nix develop
• cape test
• cape submission verify --all

Notes

• No scenario/verifier override flags added; wrapper auto-infers as per design doc. Existing submissions continue to work; scenarios with verifier.uplc will enforce expected results.