Fix tree-sitter not found after cargo install

Install-TreeSitter does not add ~/.cargo/bin to $env:PATH after
running cargo install, unlike Install-Rust which does. When Rust is
already present on the system (so Install-Rust is a no-op) and
~/.cargo/bin is not in the inherited PATH, the tree-sitter binary
cannot be found by Export-GrammarBinding.

Add the same PATH update logic that Install-Rust uses.

Contact: johan.kallio@teamtech.se

Author: skabbio1976

helpers.build.psm1

@@ -500,6 +500,19 @@ function Install-TreeSitter {
         if ($LASTEXITCODE -ne 0) {
             throw "Failed to install tree-sitter-cli"
         }
+
+        # Ensure cargo bin directory is in PATH so tree-sitter can be found
+        if (!$IsWindows) {
+            $cargoBin = "$env:HOME/.cargo/bin"
+            if ($env:PATH -notlike "*$cargoBin*") {
+                $env:PATH += ":$cargoBin"
+            }
+        } else {
+            $cargoBin = "$env:USERPROFILE\.cargo\bin"
+            if ($env:PATH -notlike "*$cargoBin*") {
+                $env:PATH += ";$cargoBin"
+            }
+        }
     }
 }