feat: Add troubleshooting guide for PowerShell execution policy errors

Author: pphatdev

docs/powershell-execution-policy.md

@@ -0,0 +1,92 @@
+# PowerShell Execution Policy Error
+
+## Problem
+
+When running `phat` commands, you see this error:
+
+```
+phat : File C:\Program Files (x86)\Phat\phat.ps1 cannot be loaded. The file C:\Program Files (x86)\Phat\phat.ps1 is
+not digitally signed. You cannot run this script on the current system. For more information about running scripts and
+setting execution policy, see about_Execution_Policies at https:/go.microsoft.com/fwlink/?LinkID=135170.
+At line:1 char:1
++ phat
++ ~~~~
+    + CategoryInfo          : SecurityError: (:) [], PSSecurityException
+    + FullyQualifiedErrorId : UnauthorizedAccess
+```
+
+## Cause
+
+Windows PowerShell has an execution policy that prevents unsigned scripts from running. By default, Windows blocks all scripts for security reasons.
+
+## Solutions
+
+### Solution 1: Set Execution Policy (Recommended)
+
+This is the recommended approach that balances security and functionality.
+
+**Step 1:** Open PowerShell as Administrator
+- Press `Win + X` and select "Windows PowerShell (Admin)" or "Terminal (Admin)"
+
+**Step 2:** Set the execution policy
+```powershell
+Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser
+```
+
+When prompted, type `Y` and press Enter.
+
+**Step 3:** Unblock the script file
+```powershell
+Unblock-File "C:\Program Files (x86)\Phat\phat.ps1"
+```
+
+**Step 4:** Test the installation
+```powershell
+phat --version
+```
+
+### Solution 2: Unblock File Only
+
+If your execution policy is already set but the script is still blocked:
+
+```powershell
+Unblock-File "C:\Program Files (x86)\Phat\phat.ps1"
+```
+
+### Solution 3: Bypass for Current Session
+
+If you only need to run Phat temporarily:
+
+```powershell
+Set-ExecutionPolicy -ExecutionPolicy Bypass -Scope Process
+```
+
+This only affects the current PowerShell session and doesn't make permanent changes.
+
+## Understanding Execution Policies
+
+| Policy | Description |
+|--------|-------------|
+| **Restricted** | No scripts allowed (Windows default) |
+| **RemoteSigned** | Local scripts run; downloaded scripts need signature (Recommended) |
+| **Unrestricted** | All scripts run with warnings for downloaded ones |
+| **Bypass** | Nothing blocked, no warnings |
+
+## Check Current Policy
+
+To see your current execution policy settings:
+
+```powershell
+Get-ExecutionPolicy -List
+```
+
+## Why RemoteSigned is Recommended
+
+- **Security**: Downloaded scripts still require a digital signature
+- **Functionality**: Your own local scripts (like Phat) can run without issues
+- **Balance**: Provides protection against malicious downloaded scripts while allowing legitimate local development
+
+## Related Resources
+
+- [PowerShell Execution Policies Documentation](https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_execution_policies)
+- [Back to Troubleshooting Index](TROUBLESHOOTING.md)