Add hermes_audio and draw the mouth from the real waveform

audio_state taps the microphone and the speaker monitor with parec and publishes
levels, a speaking/listening/quiet activity, and trigger-locked waveform windows;
audio itself stays out of ROS. The activity detector calibrates its noise floor
at start-up and absorbs steady noise, so a room at -43 dBFS does not read as
"listening" forever, and it ignores the mic while the robot speaks.

The face arbitrates the state it shows: sleeping (agent side only, so room sound
never wakes a face that means "no agent connected") > speaking > listening >
thinking > idle, and draws the mouth from the real samples while fresh scope data
exists, auto-scaled so a quiet voice is still visible.

Checked: a tone played to the sink shows as `speaking` with the mic ignored. The
microphone-to-mouth path with a live voice is not yet confirmed.

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

ros/hermes_audio/setup.py

@@ -0,0 +1,24 @@
+from setuptools import find_packages, setup
+
+package_name = 'hermes_audio'
+
+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='Audio levels and speaking/listening state for the Hermes robot.',
+    license='UNLICENSED',
+    entry_points={
+        'console_scripts': [
+            'audio_state = hermes_audio.audio_state_node:main',
+        ],
+    },
+)