v0.4: Official Houdini package system integration

- hermes_houdini_bridge.json: package descriptor (generated by install.sh)
- scripts/python/hermes_bridge_panel.py: moved to package-standard location
- python_panels/hermes_bridge.pypanel: registered in Windows menu
- install.sh: one-command installer (generates JSON with correct path)
- git clone + install.sh = fully installed; git pull = update
- Panel opens via Windows -> Hermes Bridge (no Python Shell needed)

hermes_houdini_bridge.json

@@ -0,0 +1,8 @@
+{
+    "hpath": "/home/niklas/Documents/projects_privat/hermes-houdini-bridge",
+    "env": [
+        {"HHB_PACKAGE": "/home/niklas/Documents/projects_privat/hermes-houdini-bridge"}
+    ],
+    "load_package_once": true,
+    "enable": "houdini_version >= '21.0'"
+}