feat: support named prepared statements

[mkaufmann]

Summary

Add a Hyper-specific prepared statement API for native named parameters while preserving standard JDBC positional prepared statements.

Named setters are exposed through a separate DataCloudNamedPreparedStatement rather than being added to DataCloudPreparedStatement. Hyper accepts either positional or named parameters for a query, but does not support mixing both parameter styles. Keeping them as separate statement types makes that backend constraint explicit and prevents callers from combining incompatible setters on one statement instance.

What changed

• Add DataCloudConnection.prepareNamedStatement(String) returning DataCloudNamedPreparedStatement.
• Support named setters for the driver's existing scalar parameter types, including exact quoted names such as :"order total".
• Share execution, type conversion, metadata, timeout, and parameter serialization logic between positional and named statements through a package-private base class.
• Encode named Arrow fields directly from parameter names; binding order is not significant, repeated SQL references share one binding, and rebinding replaces the value.
• Preserve typed SQL nulls where supported, encode untyped nulls compatibly with Hyper, and reject unsupported null parameter types before serialization.
• Document named parameter usage in the README.

Model: aisuite/gpt-5.6-sol · Effort: default · Co-Authored-By: Claude

[codecov]

Codecov Report

❌ Patch coverage is 83.69565% with 45 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.15%. Comparing base (9b21396) to head (ac89e81).

Files with missing lines	Patch %	Lines
...loud/jdbc/core/DataCloudPreparedStatementBase.java	84.24%	14 Missing and 9 partials ⚠️
...oud/jdbc/core/DataCloudNamedPreparedStatement.java	70.83%	14 Missing ⚠️
...force/datacloud/jdbc/protocol/data/ArrowUtils.java	63.15%	2 Missing and 5 partials ⚠️
.../datacloud/jdbc/protocol/data/VectorPopulator.java	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #197      +/-   ##
============================================
+ Coverage     80.95%   81.15%   +0.19%     
- Complexity     1723     1785      +62     
============================================
  Files           123      125       +2     
  Lines          5042     5152     +110     
  Branches        523      541      +18     
============================================
+ Hits           4082     4181      +99     
- Misses          728      729       +1     
- Partials        232      242      +10     

Components	Coverage Δ
JDBC Core	81.22% <83.69%> (+0.23%)	⬆️
JDBC Main	57.42% <ø> (ø)
JDBC HTTP	90.55% <ø> (ø)
JDBC Utilities	65.25% <ø> (ø)
Spark Datasource	∅ <ø> (∅)

Files with missing lines	Coverage Δ
...force/datacloud/jdbc/core/DataCloudConnection.java	57.34% <100.00%> (+0.30%)	⬆️
...atacloud/jdbc/core/DataCloudPreparedStatement.java	100.00% <100.00%> (+8.28%)	⬆️
.../datacloud/jdbc/protocol/data/VectorPopulator.java	83.01% <50.00%> (+2.12%)	⬆️
...force/datacloud/jdbc/protocol/data/ArrowUtils.java	73.80% <63.15%> (+2.38%)	⬆️
...oud/jdbc/core/DataCloudNamedPreparedStatement.java	70.83% <70.83%> (ø)
...loud/jdbc/core/DataCloudPreparedStatementBase.java	84.24% <84.24%> (ø)

... and 2 files with indirect coverage changes

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