CLI: validation profiles and shared reports

[zkwentz]

What & Why

The shared validation API needs a stable author-facing CLI. This PR exposes static, runtime, and full profiles plus JSON/output controls through openenv validate.

Risk & Review Guidance

• Risk level: MEDIUM — changes CLI dispatch and exit behavior
• Task class: feature
• Review focus: src/openenv/cli/commands/validate.py:30 for target/profile resolution and exit codes; tests/test_cli/test_validate.py for URL and report compatibility
• Blast radius: Bad target selection or exit semantics would break local scripts and CI gates.

Decisions & Alternatives

• Explicit profiles — callers can choose fast source checks, runtime checks, or all locally available criteria.
• Retain URL shorthand — preserves existing runtime validation ergonomics.
• JSON is the shared schema — rejected a separate CLI-only report format.

Verification

• PASS: PYTHONPATH=src:envs .venv/bin/python -m pytest tests/ -q -m 'not integration' — 1,559 passed, 114 skipped, 31 external integration tests deselected on the complete stack.
• PASS: Fork whole-stack CI — 7/7 checks passed, including Python 3.11/3.12, lint, docs, lock validation, and package smoke tests.
• NOT verified: No external deployed Space was required for the CLI contract tests.

Scope & Non-Goals

• No strict publish profile or remote Sandbox option in this layer; those are later stack entries.

Stack

PR 6 of 17; depends on #946.

Full 17-PR stack

1. #942 RFC 008: Spec-neutral local and remote validation architecture
2. #943 Validation foundation: spec-neutral contracts and adapters
3. #944 Validation policy: spec-aware check registry and planner
4. #945 Validation executor: hardened shared reports and eligibility
5. #946 Local validation API: execution-model-aware profiles
6. #947 CLI: validation profiles and shared reports ← current
7. #948 HF runtime: dedicated sandbox execution mode
8. #949 HF certification: enforce trusted dedicated isolation
9. #950 [RFC 008] Define remote author validation and publish gating
10. #951 Validation: unify CLI reports and add a strict publish profile
11. #952 Validation: add structured author diagnostics and remediation
12. #953 Validation: run author validation in dedicated HF Sandboxes
13. #954 Validation: isolate submitted code in author Sandboxes
14. #955 Validation: bind author reports to policy and source
15. #956 CLI: scaffold publish requirements
16. #957 CLI: gate pushes on staged remote validation
17. #958 Docs: explain local, remote, and publish validation

All upstream PRs remain draft while RFC 008 is under review.