[magnusp]

Why

The nine Calendar overloads of setDate/setTime/setTimestamp and getDate/getTime/getTimestamp ignored their Calendar and delegated to the default-zone overload. A caller passing Asia/Tokyo got the same text and the same instant as a caller passing UTC, which contradicts JDBC, H2, PostgreSQL, and xerial.

What changed

• Threaded a ZoneId through SqliteDateTimeValues.from, epochMillisToLocalDateTime, and parseSqliteDateTime, keeping the system-default overloads so the non-Calendar path is unchanged. Text with an explicit offset is a fixed instant converted into the zone; naive text is wall-clock time in the zone; INTEGER is epoch millis; FLOAT is a Julian day.
• Getters now build java.sql.Date/Time/Timestamp from the zone-local fields: midnight of the local date, 1970-01-01 plus the local time, and the full local date-time with nanos preserved.
• Setters render the instant in the calendar zone while keeping the existing text forms: yyyy-MM-dd, HH:mm:ss, and yyyy-MM-dd HH:mm:ss[.fraction] with .0 for zero nanos, matching Timestamp.toString(). setTimestamp does not go through JdbcValueConverter.formatTimestamp.
• A null Calendar means the JVM default zone and delegates to the existing overload; it never throws.
• Added unit coverage for zone-dependent getters and setters, offset text, INTEGER and Julian-day inputs, null calendars, null values, nanos, and a non-Gregorian calendar field system.

Blast radius

Only the nine Calendar overloads change. The default-zone overloads, setObject, getObject(..., LocalDate.class), and the Appendix B conversion paths are untouched, so existing text and instants are unchanged. A Timestamp still carries no zone: the calendar only decides which instant naive stored text denotes.

Verification

• ./mvnw -pl libsql-jdbc -Dtest='LibsqlResultSetTest,LibsqlPreparedStatementTest' test: 99 tests, 0 failures.
• ./mvnw clean verify: 1524 JDBC unit tests (1559 unit tests across the reactor), 192 itests, 271 conformance tests with 7 skipped, 0 failures. This includes the vendored StatementTest#nullDate and #emptyDate.
• ./mvnw spotless:check passes.

Fixes #237