Bring every doc up to date, and give the repo a Wi-Fi template that exists

CONTEXT.md had grown by appending and contradicted itself (all four nodes vs six, a retracted CPU
figure, "no calibration", "nobody enrolled", "audio untested as a service", the Wi-Fi-off boot as
not done, a class the tracker replaced). Rewritten as one current-state document organised by
subsystem, with fresh measurements, the owner's decisions, the gotchas, the neck's arrival-day plan
and what is genuinely still open.

README: status, speakers not fitted, new-session note for Hermes, the calibration section (shipped
calibration, coverage hints, outlier dropping, --from-views), running the tests, the docs row.
HANDOFF.md gets a status banner listing where the original brief has drifted. CLAUDE.md starts at
CONTEXT.md. The echo-cancel config no longer talks about a Pi Zero, and the enclosure guide no longer
tells you to centre a servo with a tool that does not exist yet.

pi/network-config.example is a tracked, credentials-free first-boot template: the README pointed at
pi/50-cloud-init.yaml, which is gitignored and so missing from a fresh clone. The dead IdentityCache
(replaced by the tracker) is removed. Docstrings corrected: audio scope publishing, the MCP health
topics, and what the calibration tool does.

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

ros/hermes_audio/hermes_audio/audio_state_node.py

@@ -4,8 +4,9 @@ listening. Audio itself never goes through ROS; this reads PipeWire with `parec`
 Publishes:  /audio/levels (std_msgs/Float32MultiArray): [mic_dbfs, speaker_dbfs]
             /audio/activity (std_msgs/String): speaking | listening | quiet (on change, and 2 Hz)
             /audio/scope/mic, /audio/scope/speaker (std_msgs/Float32MultiArray): a trigger-locked
-                window of `scope_samples` samples at 16 kHz in [-1, 1], while there is sound: the face
-                draws the mouth from it, so the trace is the real signal
+                window of `scope_samples` samples at 16 kHz in [-1, 1]. The mic's is published only while
+                listening and the speaker's only while speaking (idle, nothing goes out): the face draws the
+                mouth from it, so the trace is the real signal
 """
 import rclpy
 from rclpy.node import Node