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

CLAUDE.md

@@ -5,13 +5,14 @@ pan/tilt head and an oscilloscope-style face. Hardware: Raspberry Pi 4, Adafruit
 Arducam UC-346 (OV5647), two MG90S servos on GPIO12/13. Software: ROS 2 Jazzy on Ubuntu 24.04 on
 the Pi; on the hosts, ROS runs only in podman containers.
 
-**Start with `HANDOFF.md`.** It is the implementation brief: hardware facts, what exists, the
-work packages in order, acceptance checks, and the list of unverified assumptions.
+**Start with `CONTEXT.md`**: where the work really stands, what is verified, the owner's decisions, and
+what is open. `HANDOFF.md` is the original implementation brief (hardware facts, work packages,
+acceptance checks); it has drifted, so read its status banner first.
 
 - `pi/` and `ros/` run on the robot; `host/` runs on the owner's machines. `CONTEXT.md` tracks where
   the work stands; `HANDOFF.md` is the original brief and has drifted (ROS stays on the Pi, and
   `hermes_mcp` is the only bridge out; see `CONTEXT.md`).
-- Package 0a (platform proof) comes before everything; start with `host/check-pi-platform.sh`.
+- The platform is proven (`host/check-pi-platform.sh` passes and the Pi runs everything); `CONTEXT.md` says what is open.
 - `docs/face-prototype.html` is the reference for the face renderer; port it, don't ship it.
 - `enclosure/` holds the OpenSCAD model and STLs. It was built from estimates; refine it from the
   owner's caliper measurements and test prints before anyone prints the large parts.