feat(encoding): add range and delta block codecs

[Xuanwo]

Stack 3 of the generic block compression series. Depends on #8040.

This PR appends Range and Delta as CompressiveEncoding tags 14 and 15 and implements their bounded u32/u64 codec trees. Range is metadata-only; Delta inherits its child payload arity. Both readers use checked cardinality and arithmetic, and malformed trees fail during shared validation.

No production page writer selects these codecs yet. Lance 2.0–2.2 bytes, selector order, and SparseLayout wire remain unchanged.

Validation:

• cargo fmt --all
• cargo check -p lance-encoding --no-default-features --tests
• cargo check -p lance-encoding --tests --benches
• cargo test -p lance-encoding compression::block
• cargo test -p lance-encoding compression::tests
• cargo test -p lance-encoding encodings::physical
• uv run mkdocs build
• cargo clippy --all --tests --benches -- -D warnings

Stack navigation

• Umbrella / integration reference: feat(encoding): add generic block compression #8002
• Previous: refactor(encoding): make block codecs fallible #8040
• Next: feat(encoding): decode generic mini-block offsets #8042

[github-actions]

Important

This PR touches the Lance format specification.

Substantive changes to the format specification — the .proto definitions
and the spec docs under docs/src/format/ — require a PMC vote before merge.
Minor edits such as typo fixes, wording, or formatting are excluded; use your
judgment.

If this is a meaningful format change:

• Start a vote following the Lance community voting process.
  Format specification modifications need 3 binding +1 votes (excluding the
  proposer), held on GitHub Discussions, with a minimum voting period of 1 week.
• Once the vote passes, link the completed vote in this PR. It should not be
  merged until the vote is linked.

[lance-gatekeeper]

🟡 Gate recommendation: maintainer decision required.

The codec direction is technically sound and addresses the documented uncompressed-offset gap with a bounded, checked zero-or-one-payload tree.

This adds CompressiveEncoding tags 14 and 15, so it is a substantive format-specification change. Repository policy requires a separate PMC vote, but no completed vote is linked. Please link the vote covering these Range/Delta semantics, or document that an existing umbrella vote covers this stacked change.

Please mark this PR with the breaking-change label.

[Xuanwo]

Superseded by the rebuilt Range and Delta layer in #8325. The new stack is rooted at #8324 and ends at #8333; closing this obsolete layer to avoid duplicate review.