Add missing dependencies: opencv-python, psutil, libtmux

These packages are used by the app but were not declared in
pyproject.toml. A fresh install from HuggingFace would fail
without them since pip only installs declared dependencies.

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

pyproject.toml

@@ -13,6 +13,9 @@ dependencies = [
     "webrtcvad",
     "soundfile",
     "setuptools",  # webrtcvad needs pkg_resources at runtime
+    "opencv-python",  # vision: detection, pose, segmentation
+    "psutil",  # system stats: CPU, RAM, disk, network
+    "libtmux",  # shell tab: tmux session management
 ]
 keywords = ["reachy-mini-app"]