[GLUTEN-10134][VL] Add CI AI deep analysis via Copilot CLI to ANSI workflow

Integrate Copilot CLI to generate AI-powered deep analysis reports appended
to PR comments. Supports model selection via PR comment (--model flag) with
fallback chain: user-specified → claude-sonnet-4 → auto.

Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>

Author: baibaichen