Fix input parsing in gauge example

[pepperoni505]

Resolves #29

Previous logic led to an empty text field being parsed as [""], which caused an error on the Rust side since that empty string counts as a parameter, and if the query doesn't expect any, it would error. New behavior expects either nothing in the field (leading to an empty array), or a JSON formatted array.

Additionally, there was incorrect fallbacks for an empty string in the argument text field. This is now fixed

[Copilot]

Pull Request Overview

This PR fixes input parsing issues in the gauge example where empty text fields were incorrectly parsed as [""] instead of [], causing errors when queries expected no parameters. The changes standardize parameter handling and improve SQL query argument parsing.

Key Changes:

• Updated function callback signatures to use required (non-optional) parameters
• Replaced string fallback patterns from ?? "" to no fallback, and numeric fallbacks from ?? 0 to || 0
• Improved SQL query parameter parsing to use proper JSON parsing with error handling

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[Copilot]

The functionCallback signature requires two parameters (input: string, inputAlt: string), but some callbacks in the functionList (e.g., lines 48, 222) take no parameters. This creates a type mismatch. Consider making the parameters optional with (input?: string, inputAlt?: string) or handling functions with different arities differently.

Suggested change

	functionCallback: (input: string, inputAlt: string) => Promise<unknown>;
	functionCallback: (input?: string, inputAlt?: string) => Promise<unknown>;