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_mcp/hermes_mcp/mcp_node.py

@@ -2,7 +2,8 @@
 
 Serves MCP (streamable HTTP, bearer token) to Hermes on the USB link and talks to the graph locally.
 Subscribes:  image_topic (sensor_msgs/CompressedImage, default /camera/image_raw/compressed)
-             /vision/faces (vision_msgs/Detection2DArray) and /camera/camera_info, for faces() and look()
+             /vision/faces (vision_msgs/Detection2DArray) and /camera/camera_info, for faces() and look();
+             /health/* from hermes_thermal, for the health block of robot://status
 Publishes:   /hermes/state (std_msgs/String):
                `idle` once a second while an authenticated MCP client is connected: the agent heartbeat
                  the face uses to wake and, when it stops, to fall asleep ("no agent connected");