fix: use rustup for checking installed wasm32 target in tests

The previous fix (04a8b11) incorrectly used `rustc --print target-list`
which shows ALL SUPPORTED targets (hundreds), not INSTALLED targets.

This caused false positives: tests thought Rust was available, but
server correctly rejected compilation when wasm32 target wasn't installed.

Now using `rustup target list --installed` to match server's detection
logic in rust.go:52.

Fixes:
- TestE2E_ScriptingAPI_ResponseModification
- TestE2E_ScriptingAPI_BothTriggers
- TestE2E_ScriptValidation/Valid_Rust

Author: 777genius

internal/e2e/scripting_compilation_test.go

@@ -620,8 +620,14 @@ func isRustAvailable() bool {
 		return false
 	}
 
-	// Check if wasm32-unknown-unknown target is installed
-	cmd := exec.Command("rustc", "--print", "target-list")
+	// Check if rustup exists (needed to query installed targets)
+	if cmd := exec.Command("rustup", "--version"); cmd.Run() != nil {
+		return false
+	}
+
+	// Check if wasm32-unknown-unknown target is INSTALLED (not just supported)
+	// This matches the server's detection logic in rust.go:52
+	cmd := exec.Command("rustup", "target", "list", "--installed")
 	out, err := cmd.Output()
 	if err != nil {
 		return false