Add portability report to package compile and export flows

## Problem statement Authors need to see whether a compiled package is actually portable before exporting or publishing it. A pass/fail validation result is not enough when the compiler has redacted values, introduced parameters, or found assumptions that require author decisions. ## Scope - Add a human-readable portability report to compile output. - Include redactions, parameterized values, setup requirements, unresolved blockers, provider compatibility notes, and validation status. - Make report output available in normal text and future JSON-friendly structure. - Gate export/publish when blockers remain. ## Acceptance criteria - Compile output clearly reports portability status before package export. - Export/publish refuses compiled packages with unresolved portability blockers. - The report cross-references validation results from #31 and setup requirements from #72 when present. - Tests cover clean, warning-only, and blocker states. ## Dependencies - Depends on sanitization and setup-parameterization issues. - Builds on #31 validation and #72 setup playbook. ## Non-goals - No registry UI changes. - No automatic remediation for every blocker. - No JSON-only output requirement; readable CLI output comes first. ## Sequencing Final child issue in sanitization. Behavioral validation should consume the resulting package only after this report is clean.