Release Core v0.2.82 with semantic symlink-root traversal

[AntoineToussaint]

Release the generic semantic-index root fix from #198 after it merges.

Acceptance:

• version metadata advances from 0.2.81 to 0.2.82
• the release commit contains the codefly.semantic-index/v3 contract
• an annotated v0.2.82 tag points at the exact merged release commit
• downstream agents can pin the immutable release

Depends on #198.