Feat/dynamic select

[cgardev]

feat: add dynamic select with run-time projection and record accessors

Summary

This pull request adds a dynamic SELECT constructor for projections whose arity only becomes known at run time, mirroring jOOQ's DSL.select(SelectFieldOrAsterisk...) and its untyped org.jooq.Record. It also renames the library's leftover internal working name (jooq) to gooq across error messages and self-referential comments.

Motivation

The typed Select1..Select22 constructors require the projection arity at compile time. A query whose column set is assembled from a run-time value — for example a GROUP BY dimension list derived from a request — previously forced consumers into a switch over every possible arity, duplicating the query construction and row mapping once per case.

What is included

Select(fields ...AnyField) SelectFromStep[Record]

• Accepts a projection assembled at run time and composes with the entire existing clause chain: joins, Distinct, Where, GroupBy, Having, OrderBy, limits, locking, set operations, and every terminal fetch.
• Every projected field that carries a Go element type (Field[T], including aliased fields and the Raw/RawValue escape hatches) is scanned into a value of that type through a new unexported scanTarget hook on the concrete field implementation, so Record values match what the equivalent typed projection would produce, independent of the driver's native representations.
• A SQL NULL scanned into a non-nullable element type is an error, exactly as in the typed constructors; nullable columns are projected with a pointer or sql.Null* element type.
• Passing no fields mirrors the reference's empty-select convenience and renders SELECT *, taking the column names from the result set.

Record

Dynamic row type mirroring org.jooq.Record:

• Size(), Columns(), Values(), Get(index), and GetByName(name) (case-insensitive, consistent with FetchInto column matching).
• Generic accessors Value[T](record, name) and ValueAt[T](record, index) mirroring Record.get(..., Class), with deliberate conversions only: []byte relaxes to string and numeric kinds convert between one another. Anything else is an error rather than a silent reflect conversion, which would, for example, turn an integer into the string of its code point.

Rename: jooq → gooq

Error message prefixes (gooq: ...), the fake test driver name, and every comment that refers to this library itself now say gooq. References to the jOOQ Java library that inspired the design — its org.jooq package paths and website — are intentionally preserved.

Testing

• Golden SQL tests confirming the dynamic constructor renders exactly what the typed counterpart renders for the same projection.
• Fake-driver unit tests covering typed scanning, alias resolution, the SELECT * path, nullable projections, conversion errors, and the single-row terminal operations.
• New PostgreSQL and SQLite integration tests, including the motivating run-time GROUP BY arity case.
• Both CI suites (core module and integration module) pass.