refactor(h3d-carve-0): add scriptType:module to plugin.json

Zero logic changes. screen.js content byte-identical — an IIFE is valid
inside a <script type="module">. The loader consumes scriptType at
plugin-loader.js:666 (if plugin.script_type === "module" -> script.type =
"module"), fed from plugins/__init__.py:1429 (manifest.get("scriptType")).

Isolates the R7 module-flip risk as its own verifiable cut before any
function extraction begins.

Version bump: 3.34.1 → 3.35.0
Suite: 160/160 pass.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014uZ169yfoFYArXz962g7KW

plugins/highway_3d/plugin.json

@@ -1,8 +1,9 @@
 {
     "id": "highway_3d",
     "name": "3D Highway",
-    "version": "3.34.1",
+    "version": "3.35.0",
     "type": "visualization",
+    "scriptType": "module",
     "bundled": true,
     "script": "screen.js",
     "styles": "assets/plugin.css",