feat: propagate traceparent to all NAPI async entry points

[sinianluoye]

📝 Description

Propagate traceparent to all remaining async NAPI entry points that perform I/O, so Rust-side tracing spans share the same traceId as the calling TypeScript code. Previously only query.execute, table.add, table.update, table.delete, table.countRows, table.createIndex, and table.optimize received a traceparent — all other async functions produced orphaned traces.

Rust changes

• connection.rs: Added traceparent: Option<String> + napi_span! + .instrument(span) to 7 functions: table_names, create_table, create_empty_table, open_table, clone_table, drop_table, drop_all_tables
• iterator.rs: Store traceparent field in RecordBatchIterator, use in next() with napi_span! + .instrument(span)
• query.rs: Pass traceparent to RecordBatchIterator::new() in all 3 execute() methods (Query, VectorQuery, TakeQuery)
• merge.rs: Added traceparent to execute() + napi_span! + .instrument(span)

TypeScript changes

• connection.ts: Import getTraceparent, pass await getTraceparent() to all 7 NAPI calls
• merge.ts: Import getTraceparent, pass await getTraceparent() to execute()

Verification

• cargo check passes (both with and without profiling-otlp feature)
• tsc --noEmit passes
• All 504 existing tests pass (12/12 test suites)

✅ Checklist

• My PR title follows the type(scope): description format (lowercase).
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• My changes generate no new warnings.

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