Only show certain Scratch extensions (#1388)

ACs ✅

- [x] When clicking on the extensions panel (the purple button in the
bottom left) only the 5 extensions listed below should be visible
Visible extensions: Music, Pen, Video Sensing, Face Sensing, Makey Makey

Applied CSS fix as discussed

<img width="1485" height="543" alt="image"
src="https://github.com/user-attachments/assets/67fec780-53d1-4fed-bac7-9234a68d3544"
/>

Author: abcampo-iry

src/assets/stylesheets/Scratch.scss

@@ -64,4 +64,17 @@ div.injectionDiv {
   border-end-start-radius: 8px;
 }
 
+/*
+ * Hide extensions we do not currently support reliably in this deployment.
+ */
+#text2speech,
+#translate,
+#microbit,
+#gdxfor,
+#ev3,
+#boost,
+#wedo2 {
+  display: none;
+}
+
 /* stylelint-enable selector-class-pattern */