feat(rust): propagate SEA manifest metadata through Arrow schema

[vikrantpuppala]

Summary

• Propagate SEA manifest column metadata (type_name, type_text, type_precision, type_scale, type_interval_type) through the Arrow C Data Interface FFI boundary as databricks.* field-level key-value metadata
• Enables the C++ ODBC driver to read server-provided metadata instead of reverse-engineering it from Arrow type IDs — fixing systematic diffs in nullable, precision, scale, display_size, octet_length, and type_name
• All paths that export Arrow streams (Statement::execute, metadata FFI functions) now carry the manifest through

Changes

File	Change
src/types/sea.rs	Add type_precision, type_scale, type_interval_type to ColumnInfo
src/reader/mod.rs	Add metadata_keys constants + augment_schema_with_manifest()
src/reader/mod.rs	Update ResultReaderAdapter::new() to accept optional manifest
src/client/mod.rs	Add manifest: Option<ResultManifest> to ExecuteResult
src/client/sea.rs	Pass response.manifest through to ExecuteResult
src/statement.rs	Pass manifest to ResultReaderAdapter::new()
src/ffi/metadata.rs	Pass manifest through export_reader() for all metadata FFI functions

Test plan

• Unit tests for ColumnInfo deserialization with/without optional fields
• Unit tests for augment_schema_with_manifest (basic types, DECIMAL precision/scale, INTERVAL, missing ColumnInfo, preserves existing metadata)
• Unit tests for ResultReaderAdapter with and without manifest
• E2E test (metadata_propagation_test example) verifying metadata flows through for INT, LONG, STRING, BOOLEAN, DOUBLE, FLOAT, SHORT, BYTE, DECIMAL(10,2), DECIMAL(18,5), DECIMAL(38,0), DATE, TIMESTAMP, ARRAY, MAP, STRUCT, BINARY
• ODBC cross-driver comparator (after C++ consumer PR lands)

This pull request was AI-assisted by Isaac.

[gopalldb]

O(n*m) column lookup in augment_schema_with_manifest

let col_info = columns.iter().find(|c| c.position as usize == i);

For each of the n schema fields, this scans all m manifest columns. For typical queries (<100 columns) this is fine, but SELECT * on wide tables (1000+ columns) would be O(n²). Simple fix:

let col_by_pos: HashMap<usize, &ColumnInfo> = columns
.iter()
.map(|c| (c.position as usize, c))
.collect();

[vikrantpuppala]

Good catch — switched to a HashMap<usize, &ColumnInfo> built upfront. O(n+m) now.

[gopalldb]

position is i32 but used as usize without bounds check

c.position as usize == i

If the server ever returns a negative position, as usize wraps to a huge value silently. Add a guard:

let col_info = columns.iter().find(|c| c.position >= 0 && c.position as usize == i);

Or better, use usize::try_from(c.position).ok().

[vikrantpuppala]

Fixed — using usize::try_from(c.position).ok() in the HashMap construction, so negative positions are silently filtered out instead of wrapping.

[gopalldb]

LG, some minor comments