Add colorful table formatting features and corresponding tests

[lescoggi]

Fixes #1

[Copilot]

Pull Request Overview

This PR adds colorful table formatting capabilities to the Excel features library, accompanied by new tests and updated documentation.

• Introduces methods to create and apply styled tables, conditional formatting, and custom borders.
• Adds corresponding unit tests to verify each new feature.
• Updates README with usage details for the new formatting tools.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/test/java/dev/lescoggi/ExcelFeaturesTest.java	Added tests for createFormattedTable, applyTableFormatting, applyConditionalFormatting, and applyCustomBorders
README.md	Documented the new colorful table formatting tools, themes, and usage examples

Comments suppressed due to low confidence (5)

README.md:62

• The argument name colorTheme in the Apply Table Formatting section differs from theme used elsewhere. Consider standardizing on one term to avoid confusion.

`colorTheme` - Color theme: `blue`, `green`, `orange`

src/test/java/dev/lescoggi/ExcelFeaturesTest.java:138

• [nitpick] We test explicit themes but not the default behavior when theme is omitted or null. Consider adding a test for the default theme fallback.

var response = excelFeatures.createFormattedTable(workbookPath, SHEET_NAME, tableData, "blue", true);

src/test/java/dev/lescoggi/ExcelFeaturesTest.java:173

• The cell range "A0:C2" is not a valid Excel reference (rows start at 1). Please update to something like "A1:C3" or the intended 1-based range.

var response = excelFeatures.applyTableFormatting(workbookPath, SHEET_NAME, "A0:C2", "blue", true);

src/test/java/dev/lescoggi/ExcelFeaturesTest.java:188

• Using "A0:C2" here will likely cause an invalid range error at runtime. Adjust to a valid reference, for example "A1:C3".

var response = excelFeatures.applyConditionalFormatting(
            workbookPath, SHEET_NAME, "A0:C2", "greater_than", "50", "red");

src/test/java/dev/lescoggi/ExcelFeaturesTest.java:203

• The range "A0:C1" is invalid in Excel; consider starting at row 1 (e.g., "A1:C2").

var response = excelFeatures.applyCustomBorders(
            workbookPath, SHEET_NAME, "A0:C1", "thick", "blue");