feat: Add troubleshooting guide for PHP version not found errors

Author: pphatdev

docs/php-version-not-found.md

@@ -0,0 +1,73 @@
+# PHP Version Not Found
+
+## Problem
+
+Running `phat switch [version]` says the version isn't found even though you believe it's installed.
+
+## Cause
+
+Phat looks for PHP installations using a specific naming convention. If the folder name doesn't match the expected pattern, Phat won't recognize it.
+
+## Solution
+
+Make sure the PHP folder is named correctly. Phat looks for folders named `php[version]`, for example:
+
+### Correct Naming Examples
+
+✅ **Correct:**
+- `C:\xampp\php7.4.33`
+- `C:\xampp\php8.2.27`
+- `C:\xampp\php8.3.15`
+- `C:\xampp\php8.1.0`
+
+❌ **Incorrect:**
+- `C:\xampp\php-7.4.33` (contains dash)
+- `C:\xampp\PHP7.4.33` (uppercase PHP)
+- `C:\xampp\php_7.4.33` (contains underscore)
+- `C:\xampp\php-7.4` (incomplete version)
+
+### Active PHP Version
+
+The currently active version should be in a folder named exactly:
+```
+C:\xampp\php
+```
+
+## Checking Installed Versions
+
+List all recognized PHP versions:
+
+```powershell
+phat list
+```
+
+This will show which versions Phat can detect.
+
+## Renaming Folders
+
+If your folder is named incorrectly:
+
+1. Stop Apache if it's running
+2. Rename the folder to match the correct pattern
+3. Run `phat list` to verify Phat can now see it
+
+### Example
+
+If you have `C:\xampp\php-8.2.27`, rename it to:
+```
+C:\xampp\php8.2.27
+```
+
+## Verification
+
+After renaming, verify the version is detected:
+
+```powershell
+phat list
+```
+
+You should see your version in the output.
+
+## Related Resources
+
+- [Back to Troubleshooting Index](TROUBLESHOOTING.md)