feat(llm-security): add /security ide-scan — VS Code / JetBrains extension prescan (v6.3.0)

New standalone scanner (prefix IDE) discovers installed VS Code extensions
across forks (Cursor, Windsurf, VSCodium, code-server, Insiders, Remote-SSH)
and runs 7 IDE-specific threat checks: blocklist match (CRITICAL),
theme-with-code, sideload (unsigned .vsix), dangerous uninstall hook (HIGH),
wildcard activation, extension-pack expansion, typosquat (MEDIUM).

Per-extension reuse of UNI/ENT/NET/TNT/MEM/SCR scanners with bounded
concurrency. Offline-first; --online opt-in. JetBrains discovery stubbed
for v1.1. 22 new tests (1296 total, was 1274).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

plugins/llm-security/tests/fixtures/ide-extensions/root-benign/publisher.benign-ext-1.0.0/extension.js

@@ -0,0 +1,6 @@
+// benign-ext entry point
+function activate(context) {
+  console.log('benign-ext activated');
+}
+function deactivate() {}
+module.exports = { activate, deactivate };

plugins/llm-security/tests/fixtures/ide-extensions/root-benign/publisher.benign-ext-1.0.0/package.json

@@ -0,0 +1,14 @@
+{
+  "publisher": "publisher",
+  "name": "benign-ext",
+  "version": "1.0.0",
+  "displayName": "Benign Extension",
+  "description": "A normal extension with no issues",
+  "engines": { "vscode": "^1.80.0" },
+  "main": "./extension.js",
+  "activationEvents": ["onCommand:benign.hello"],
+  "contributes": {
+    "commands": [{ "command": "benign.hello", "title": "Say Hello" }]
+  },
+  "categories": ["Other"]
+}