Make the math parser allow a number's implicit multiplication after a non-number operand

[Keavon]

Makes x 2 valid, not just 2 x or 2x. Numbers on the right side still can't start with a decimal point, so .5x and .5 x are fine but x.5 and x .5 still are not.

Partly closes #2026

[cubic-dev-ai]

No issues found across 3 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Re-trigger cubic}