Add Linux build support and fix test argv handling

- BUILD-GUIDE.md: Add full Linux build instructions alongside Windows
  (system deps, depot_tools setup, gn/ninja paths for both platforms)
- README.md: Update downloads section and usage examples for Linux
- test/cdp-test.js: Fix argv parsing to handle --no-sandbox and other
  Electron flags that shift argument positions

Verified with successful Linux x64 build (Electron v43.0.0-nightly)
and automated stress test: p99 20ms, 0% messages >50ms.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

test/package-lock.json

@@ -0,0 +1,36 @@
+{
+  "name": "ws-starvation-test",
+  "version": "1.0.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "ws-starvation-test",
+      "version": "1.0.0",
+      "dependencies": {
+        "ws": "^8.0.0"
+      }
+    },
+    "node_modules/ws": {
+      "version": "8.20.0",
+      "resolved": "https://registry.npmjs.org/ws/-/ws-8.20.0.tgz",
+      "integrity": "sha512-sAt8BhgNbzCtgGbt2OxmpuryO63ZoDk/sqaB/znQm94T4fCEsy/yV+7CdC1kJhOU9lboAEU7R3kquuycDoibVA==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=10.0.0"
+      },
+      "peerDependencies": {
+        "bufferutil": "^4.0.1",
+        "utf-8-validate": ">=5.0.2"
+      },
+      "peerDependenciesMeta": {
+        "bufferutil": {
+          "optional": true
+        },
+        "utf-8-validate": {
+          "optional": true
+        }
+      }
+    }
+  }
+}