Update Readme.md and Changelog.md

Add hyperlink support (in-memory + streaming) + update README & CHANG…

…ELOG

- Added XL.Hyper(url, text) helper
- Added hyperlink support in WorksheetBuilder (in-memory)
- Added hyperlink support in StreamingWorksheetWriter (streaming)
- Updated Program.cs with new examples
- Updated README.md with hyperlink documentation + badges
- Updated CHANGELOG to Keep a Changelog format
- Updated .csproj to v1.2.0 with .NET 8/9/10 multi-targeting
- Ensures ECMA-376 compliant hyperlink generation (no Excel repair)

v1.1.0 Release Notes

- Added AddEmptyRows(int) to create true blank rows in in-memory mode.
- Added WriteEmptyRows(int) to support blank rows in streaming mode.
- Improved header detection: first non-empty row becomes the header.
- Fixed table range calculation to use actual header row index.
- Fixed AutoFilter range to respect correct header row position.
- Eliminated Excel “Repaired Records” errors caused by incorrect table parts.
- Added schema-validation unit tests for both in-memory and streaming modes.
- Improved overall OpenXML schema compliance.

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