chore: add root package.json, lock files, and gitignore *.tgz

- Root package.json (workspace definition) was missing from initial commit
- Commit root package-lock.json for reproducible installs
- Commit packages/homebridge-plugin/package-lock.json
- Add *.tgz to .gitignore (built npm tarballs are release assets, not source)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package.json

@@ -0,0 +1,14 @@
+{
+  "name": "wemo-manager",
+  "version": "2.0.0",
+  "private": true,
+  "workspaces": [
+    "packages/*",
+    "apps/*"
+  ],
+  "scripts": {
+    "dev": "npm run dev --workspace=apps/desktop",
+    "build": "npm run build --workspace=apps/desktop",
+    "install:all": "npm install"
+  }
+}