XLSX documentation skill hides sheets; Excel flags them as corrupt and removes them

**Description**
When using the documentation XLSX skill, some worksheets are being created as **hidden**. When the resulting `.xlsx` file is opened in Microsoft Excel, Excel reports that the workbook is corrupted and automatically removes the hidden sheets during its repair process.

This leads to data loss and an inconsistent experience between what the skill generates and what the user actually sees in Excel.

I suggest adding an explicit **"DO NOT HIDE SHEETS"** directive (or configuration option) to the XLSX skill so that all generated sheets remain visible by default and are not treated as corrupt by Excel.

**Steps to Reproduce**

1. Use the documentation XLSX skill to generate an Excel workbook.
2. Save the generated `.xlsx` file.
3. Open the file in Microsoft Excel (desktop).
4. Observe Excel’s repair dialog and the message that some sheets are corrupt/removed.
5. After repair, check the workbook: previously hidden sheets are gone.

**Expected Behavior**

* Excel should open the generated `.xlsx` file without any repair or corruption warnings.
* All generated sheets (including those the skill currently hides) should remain intact and accessible.
* No automatic removal of sheets by Excel.

**Actual Behavior**

* Excel displays a corruption/repair dialog on open.
* Excel “repairs” the file and removes the hidden sheets.
* Resulting workbook is missing content that was generated by the XLSX skill.

**Environment**

* XLSX documentation skill (current version)
* Microsoft Excel (desktop, recent version; observed on Windows)

**Proposed Solution**

* Add a **"DO NOT HIDE SHEETS"** directive or config flag to the XLSX documentation skill.
* Default behavior: **do not hide any sheets** in the generated `.xlsx` file, especially if this risks triggering Excel’s corruption detection and automatic repair.
* Optionally allow advanced users to explicitly opt-in to hidden sheets via configuration, with clear warnings about potential Excel repair behavior.