fix: include tools/ in npm package files (#904)

The tools/ directory containing canvas_ui_tool.py was missing from the
package.json 'files' list, so it was not shipped in the published npm
tarball. Users running the released 'agent-canvas' CLI would get:

  KeyError: "ToolDefinition 'canvas_ui' is not registered"
  Failed to import module 'canvas_ui_tool': No module named 'canvas_ui_tool'

because the agent-server couldn't find the Python module that
dev-safe.mjs exposes via OH_EXTRA_PYTHON_PATH.

Co-authored-by: openhands <openhands@all-hands.dev>

package.json

@@ -174,7 +174,8 @@
     "bin",
     "build",
     "config",
-    "scripts"
+    "scripts",
+    "tools"
   ],
   "exports": {
     ".": {