[Feature] CLI Behavior Validation Suite

[djm81]

Feature: CLI Behavior Validation Suite

Parent Epic: #285 CLI End-User Validation

Groups the complete CLI end-user validation suite: behavior contract standard, output snapshot stability, misuse safety, acceptance test runner, CI integration, and copilot test generation.

Child User Stories

• [Change] CLI Behavior Contract Standard #279 — cli-val-01 (behavior contract standard) — open
• [Change] Output Snapshot Stability #280 — cli-val-02 (output snapshot stability) — open
• [Change] Misuse Safety Proof #281 — cli-val-03 (misuse safety proof) — open
• [Change] Acceptance Test Runner #282 — cli-val-04 (acceptance test runner) — open
• [Change] CLI Validation CI Integration #283 — cli-val-05 (CI integration) — open
• [Change] Copilot Test Generation for CLI Scenarios #284 — cli-val-06 (copilot test generation) — open