Add windows-shell-reliability skill (#386)

* Add windows-shell-reliability skill

* Fix validation errors in windows-shell-reliability skill

* fix(windows-shell-reliability): Correct shell guidance

Scope the UTF-8 workaround to older Windows PowerShell behavior,\ninclude stderr in the logging recipe, and replace the foreground\nredirection example with a true detached Start-Process pattern.

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Co-authored-by: sickn33 <sickn33@users.noreply.github.com>

skills/windows-shell-reliability/SKILL.md

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+---
+name: windows-shell-reliability
+description: "Reliable command execution on Windows: paths, encoding, and common binary pitfalls."
+risk: safe
+source: community
+date_added: "2026-03-19"
+---
+
+# Windows Shell Reliability Patterns
+
+> Best practices for running commands on Windows via PowerShell and CMD.
+
+## When to Use
+Use this skill when developing or debugging scripts and automation that run on Windows systems, especially when involving file paths, character encoding, or standard CLI tools.
+
+---
+
+## 1. Encoding & Redirection
+
+### CRITICAL: Redirection Differences Across PowerShell Versions
+Older Windows PowerShell releases can rewrite native-command output in ways that break
+later processing. PowerShell 7.4+ preserves the byte stream when redirecting stdout,
+so only apply the UTF-8 conversion workaround when you are dealing with older shell
+behavior or a log file that is already unreadable.
+
+| Problem | Symptom | Solution |
+|---------|---------|----------|
+| `dotnet > log.txt` | `view_file` fails in older Windows PowerShell | `Get-Content log.txt | Set-Content -Encoding utf8 log_utf8.txt` |
+| `npm run > log.txt` | Need a UTF-8 text log with errors included | `npm run ... 2>&1 | Out-File -Encoding UTF8 log.txt` |
+
+**Rule:** Prefer native redirection as-is on PowerShell 7.4+, and use explicit UTF-8
+conversion only when older Windows PowerShell redirection produces an unreadable log.
+
+---
+
+## 2. Handling Paths & Spaces
+
+### CRITICAL: Quoting
+Windows paths often contain spaces.
+
+| ❌ Wrong | ✅ Correct |
+|----------|-----------|
+| `dotnet build src/my project/file.fsproj` | `dotnet build "src/my project/file.fsproj"` |
+| `& C:\Path With Spaces\bin.exe` | `& "C:\Path With Spaces\bin.exe"` |
+
+**Rule:** Always quote absolute and relative paths that may contain spaces.
+
+### The Call Operator (&)
+In PowerShell, if an executable path starts with a quote, you MUST use the `&` operator.
+
+**Pattern:**
+```powershell
+& "C:\Program Files\dotnet\dotnet.exe" build ...
+```
+
+---
+
+## 3. Common Binary & Cmdlet Pitfalls
+
+| Action | ❌ CMD Style | ✅ PowerShell Choice |
+|--------|-------------|---------------------|
+| Delete | `del /f /q file` | `Remove-Item -Force file` |
+| Copy | `copy a b` | `Copy-Item a b` |
+| Move | `move a b` | `Move-Item a b` |
+| Make Dir | `mkdir folder` | `New-Item -ItemType Directory -Path folder` |
+
+**Tip:** Using CLI aliases like `ls`, `cat`, and `cp` in PowerShell is usually fine, but using full cmdlets in scripts is more robust.
+
+---
+
+## 4. Dotnet CLI Reliability
+
+### Build Speed & Consistency
+| Context | Command | Why |
+|---------|---------|-----|
+| Fast Iteration | `dotnet build --no-restore` | Skips redundant nuget restore. |
+| Clean Build | `dotnet build --no-incremental` | Ensures no stale artifacts. |
+| Background | `Start-Process dotnet -ArgumentList 'run' -RedirectStandardOutput output.txt -RedirectStandardError error.txt` | Launches the app without blocking the shell and keeps logs. |
+
+---
+
+## 5. Environment Variables
+
+| Shell | Syntax |
+|-------|--------|
+| PowerShell | `$env:VARIABLE_NAME` |
+| CMD | `%VARIABLE_NAME%` |
+
+---
+
+## 6. Long Paths
+Windows has a 260-character path limit by default.
+
+**Fix:** If you hit long path errors, use the extended path prefix:
+`\\?\C:\Very\Long\Path\...`
+
+---
+
+## 7. Troubleshooting Shell Errors
+
+| Error | Likely Cause | Fix |
+|-------|-------------|-----|
+| `The term 'xxx' is not recognized` | Path not in $env:PATH | Use absolute path or fix PATH. |
+| `Access to the path is denied` | File in use or permissions | Stop process or run as Admin. |
+| `Encoding mismatch` | Older shell redirection rewrote the output | Re-export the file as UTF-8 or capture with `2>&1 | Out-File -Encoding UTF8`. |
+
+---