[littlegrasscao]

Summary

• add Delta Sharing GET /shares/{share}/schemas/{schema}/tables/{table}/metadata to OpenSharingProtocolService
• return NDJSON (protocol then metaData) with Delta-Table-Version and the delta-sharing-capabilities format actually used
• parquet format by default; responseformat=delta (preferred whenever listed) wraps Kernel's protocol and metadata as deltaProtocol / deltaMetadata
• support optional version or timestamp (mutually exclusive); latest when neither is set
• resolve explicit table shares and tables discovered through a shared schema, reading the Delta log with credentials the catalog vends to the share owner
• reject unknown capability keys or response formats as INVALID_PARAMETER_VALUE

Testing

• mvn clean install: 154 tests passed
• ProtocolTableMetadataTest reads real Delta logs written to a temp directory (shared with the version test through LocalDeltaTableSupport): parquet and delta formats, historical version and timestamp, invalid capabilities, mutually exclusive parameters, version past the latest, ungranted share
• ProtocolTableMetadataIntegrationTest ran against the AWS test tables, including the deletion-vectors table (skipped without credentials)
• unit tests for DeltaSharingCapabilities and TableActions

Stacked on #105.