feat: support exponential notation in CalcCraft input and output

[pk72]

• Update regex patterns in src/table-evaluator.ts and src/main.ts to recognize and parse input exponential notation (e.g., 1e9, 2.5e-3) when scanning cell values, unit strings, and math formulas.
• Update formatNumber in src/main.ts to format and output calculated numbers in exponential notation if their absolute value crosses user-defined upper or lower limits.
• Implement settings in src/settings.ts to allow users to configure the exponent thresholds (defaulting to 10^9 and 10^-4) governing when output numbers convert to scientific notation.
• Apply the user's precision configuration to control the number of decimal places displayed in the formatted output numbers.
• Maintain full support for decimal and grouping separators (e.g., commas and periods) when both parsing input and formatting output numbers in exponential notation.