Preserve V2 partition bounds after schema promotion

[osipovartem]

Summary

• Keep historical manifest-list bounds at their original encoded width when copying entries, while preserving scan-time promotion.
• Avoid reusing manifests written under incompatible partition types; normalize survivor and tombstone partition values on same-spec copy-on-write rewrites.
• Fail explicitly on copy-on-write across a changed partition spec instead of mislabeling old transformed values.

Verification

• cargo +1.94.0 test --locked --offline -p iceberg-rust --lib: 187 passed, 2061 ignored.
• Focused manifest-list spec tests: 9 passed.
• cargo +1.94.0 clippy --locked --offline -p iceberg-rust -p iceberg-rust-spec --all-targets -- -D warnings: passed.
• Independent read-only review: APPROVED.