Add comprehensive tests for all CRUD operations

[dannywillems]

Description

Add comprehensive tests for all type-safe query builders to ensure correctness:

Tests Needed

TypedSelect

• Select specific columns
• Select all columns
• WHERE clauses (eq, gt, lt, like, in_list, etc.)
• ORDER BY (asc/desc)
• LIMIT and OFFSET
• Complex WHERE with AND/OR

TypedInsert

• Single row insert
• All column types (string, int, bool, etc.)
• Compile-time column validation

TypedUpdate

• SET single column
• SET multiple columns
• WHERE clause
• Compile-time column validation

TypedDelete

• Simple WHERE
• Complex WHERE
• Compile-time column validation

Acceptance Criteria

• All tests pass
• Tests are in tests/ directory or as unit tests
• Tests verify both SQL output and parameter handling

[dannywillems]

Covered by 154 parser integration tests (PR #14, #16) and existing builder unit tests in oxide-sql-core.