Add hermes_face ROS package and verify the display on the Pi

The Pi (hermes-bot) is flashed, upgraded and running ROS 2 Jazzy. The ST7789
works through Blinka on lgpio: pass cs=None (the kernel owns CE0), and the glass
sits at y_offset=80 in the controller RAM for every rotation, since the driver
rotates in software. The mounted pose needs rotation=270.

hermes_face is a numpy port of the flat face from docs/face-prototype.html, with
phosphor and vector styles, plus a new `sleeping` pose for "no agent connected".
The renderer has no ROS or hardware imports. The tone map is a lookup table and
the glow runs at half resolution, so the face reaches ~28 fps on the panel at
24% of a core (20 fps) to 40% (30 fps) with the CPU at full clock.

CONTEXT.md now records the Pi, the cloud-init first-boot-only gotcha, and what
is left. pi/50-cloud-init.yaml is a gitignored Wi-Fi template.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AFN8nRRCiDiMN7ChBpHJhs

ros/hermes_face/setup.py

@@ -0,0 +1,25 @@
+from setuptools import find_packages, setup
+
+package_name = 'hermes_face'
+
+setup(
+    name=package_name,
+    version='0.1.0',
+    packages=find_packages(exclude=['test']),
+    data_files=[
+        ('share/ament_index/resource_index/packages', ['resource/' + package_name]),
+        ('share/' + package_name, ['package.xml']),
+    ],
+    install_requires=['setuptools'],
+    zip_safe=True,
+    maintainer='K. Isom',
+    maintainer_email='noreply@example.com',
+    description='Oscilloscope-phosphor face for the Hermes robot.',
+    license='UNLICENSED',
+    entry_points={
+        'console_scripts': [
+            'face_node = hermes_face.face_node:main',
+            'demo = hermes_face.demo:main',
+        ],
+    },
+)