fix: installer auto-adds mosaic bin to PATH with clear status output

- install.sh: detects shell profile (zsh/bash/profile), adds PATH entry if missing
- install.ps1: adds to User PATH via SetEnvironmentVariable if missing
- Both are idempotent — show "already in PATH ✓" on re-run
- mosaic/mosaic.ps1: accept "help" and "version" as bare subcommands

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

install.ps1

@@ -66,8 +66,21 @@ catch {
     Write-Host "[mosaic-install] WARNING: doctor reported issues (run mosaic-doctor.ps1 -FailOnWarn)" -ForegroundColor Yellow
 }
 
+# Ensure mosaic bin is in User PATH persistently
+$mosaicBin = Join-Path $TargetDir "bin"
+$userPath = [Environment]::GetEnvironmentVariable("Path", "User")
+if ($userPath -and $userPath.Split(";") -contains $mosaicBin) {
+    Write-Host "[mosaic-install] PATH: $mosaicBin already in User PATH ✓"
+}
+else {
+    $newPath = if ($userPath) { "$mosaicBin;$userPath" } else { $mosaicBin }
+    [Environment]::SetEnvironmentVariable("Path", $newPath, "User")
+    $env:Path = "$mosaicBin;$env:Path"
+    Write-Host "[mosaic-install] PATH: Added $mosaicBin to User PATH ✓"
+    Write-Host "[mosaic-install] Open a new terminal for PATH changes to take effect."
+}
+
 Write-Host "[mosaic-install] Done."
-Write-Host "[mosaic-install] Add to PATH: `$env:USERPROFILE\.config\mosaic\bin"
 
 $soulPath = Join-Path $TargetDir "SOUL.md"
 if (-not (Test-Path $soulPath)) {