Refresh SizeMeasure support and make archived row decoding fallible - #51

Refreshes the original SizeMeasure work onto current main, modernizes dependencies, and closes the archived-row safe-API soundness issue.

Changes

• adds an overridable SizeMeasurable::default_aligned_size type-level helper
• adds generic primitive-array sizing while preserving the existing array alignment contract
• adds SizeMeasure support for non-generic fieldless enums, measured from the explicitly named rkyv archived representation
• rejects payload-bearing enums instead of guessing a data-dependent size
• handles struct and enum macro generation through the same syn::Result path
• updates DataBucket to 0.5.0 and data_bucket_derive to 0.3.17
• updates WorkTablesIndex to 0.0.3 and declares rkyv 0.8.17 as the minimum
• removes the unused rkyv 0.7 and other unused dependencies from the proc-macro crate
• replaces archived-row raw-pointer walking with bounds-checked offsets and unconditional rkyv validation
• returns structured DataDecodeError values for unsupported schemas and short, malformed, or misaligned archives
• documents and tests why field validation retains the complete serialized prefix for out-of-line relative pointers

Breaking API and versioning

DataBucket is bumped to 0.5.0 because this soundness correction intentionally changes public decoding contracts:

• parse_archived_row now returns Result<Vec, DataDecodeError>
• DataType::from_archived_bytes returns Result
• the legacy safe raw-pointer DataType methods are removed
• DataIterator items carry DataDecodeError

The derive crate remains 0.3.17 because its public changes are additive and its generated-code correction is compatible.

Persistence compatibility

This PR does not intentionally change the archive or page format. Generic primitive arrays deliberately retain align() == None, matching the existing u8 array implementations, and regression tests cover the old 20-byte and 32-byte behavior. rkyv guarantees format compatibility across the 0.8 release line.

Validation

• cargo build --verbose
• cargo test --verbose: 49 DataBucket tests passed
• cargo test -p data_bucket_derive
• cargo test -p data_bucket --no-default-features
• cargo clippy --all-targets --all-features -- -D warnings
• data_bucket_derive 0.3.17 publish dry-run
• WorkTable 0.9.4 all-target/all-feature downstream check with DataBucket 0.5.0 and WorkTablesIndex 0.0.3
• web3.trading-backend downstream check
• api.support.cafe workspace/all-target check with s3-sync enabled

The DataBucket package dry-run must follow publication of its exact data_bucket_derive 0.3.17 dependency. Live api.support.cafe S3 validation is intentionally deferred.

Release order after merge: data_bucket_derive 0.3.17, then data_bucket 0.5.0.

Fixes #61