fix(d1): preserve unary operators in processCol to support leading + and -

[treeder]

Summary

Fixes an issue where column identifiers with leading unary operators (e.g. +threads.showAt or -threads.score) were mangled by processCol() into invalid SQL like json_extract(threads.+threads, '$.showAt'), causing SQLite near "+": syntax error.

What changed

• In processCol(), extract any leading unary operator (+ or -) before running prefixing and JSON sub-property extraction, then reattach it to the resulting column expression.
• Added tests in test/test_order.test.js covering:
  • Query integration tests sorting with +users.name and (+users.name).
  • Unit tests asserting processCol behavior with qualified and unqualified unary expressions and JSON paths.

[github-actions]

📋 Review Summary

This pull request adds support for leading unary operators (such as + and -) in D1.processCol, preventing unary operators from interfering with table prefixing or SQLite JSON path extraction during query ordering. It also introduces unit and integration tests covering unary operator handling. However, the assertions for test case 4 in test/test_order.test.js were accidentally removed during the update and should be restored.

🔍 General Feedback

• Preserving leading unary operators in processCol cleanly enables SQLite idioms like unary + (to suppress index utilisation) and unary - (for inverted sorting).
• The defensive typeof col !== 'string' check added at the beginning of processCol is a good addition to prevent runtime type errors if non-string values are passed.

📊 Token Usage & Cost Efficiency

Metric	Value
Input Tokens (uncached)	52,469
Output Tokens	479
Total Session Tokens	64,995
Cost (uncached input)	$0.0394
Cost (output)	$0.0018
Estimated Total Cost	$0.0411

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