[codex] Reflow policy and report schema docs

[stacknil]

Brief Design Summary

This PR hard-reflows the policy and JSON report schema documentation so the Markdown source is readable in raw views and future diffs.

It preserves the v0.8 policy explainability semantics from the previous PR: policy finding explanation fields remain documented as local policy-decision metadata, not dependency safety verdicts, CVE results, or proof that a package is safe or unsafe.

No runtime behavior, CLI flags, JSON schema, Markdown/SARIF output behavior, workflows, package metadata, release tags, or publishing status changed.

Files Changed

• tools/sbom-diff-and-risk/docs/report-schema.md
• tools/sbom-diff-and-risk/docs/policy-schema.md

Validation

• git diff --check passed.
• Broad Unicode Cf/Cc scan found no non-tab/newline control or format characters.
• Confirmed both touched docs have zero source lines over 120 characters.
• Confirmed package version remains 0.7.0.
• Confirmed no workflow files changed.

Out of Scope

• No runtime behavior changes
• No CLI behavior changes
• No JSON schema changes
• No workflow changes
• No package version bump
• No tag or GitHub Release
• No PyPI/TestPyPI publishing
• No production PyPI workflow