chore: remove deprecated Pulse+ agent metrics and add audit log rotation docs

Removed all legacy Pulse+ agent metrics infrastructure (cloud-relay) which has been
fully replaced by the new docker agent and temperature agent implementations.

Changes:
- Remove cloud-relay directory and all related binaries (relay, relay-linux, etc.)
- Remove Pulse+ documentation (AGENT_METRICS_IMPLEMENTATION.md, AGENT_METRICS_SETUP.md)
- Clean up pulse-relay references in workflows and release checklist
- Add audit log rotation documentation for sensor proxy hash-chained logs
- Update .gitignore to remove cloud-relay/ entry

The new docker and temp agents remain fully functional and unaffected by this cleanup.

.github/workflows/README.md

@@ -4,7 +4,7 @@
 
 **File**: `update-demo-server.yml`
 
-Automatically updates the public demo server (`pulse-relay`) when a new stable release is published.
+Automatically updates the public demo server when a new stable release is published.
 
 ### Configuration Required
 
@@ -38,11 +38,6 @@ To test without publishing a release:
 2. Select `Update Demo Server` workflow
 3. Click `Run workflow` (if manual trigger is enabled)
 
-Or test manually:
-```bash
-ssh pulse-relay "curl -fsSL https://raw.githubusercontent.com/rcourtman/Pulse/main/install.sh | sudo bash"
-```
-
 ### Benefits
 
 - ✅ Demo server always showcases latest stable release

.gitignore

@@ -148,7 +148,6 @@ tmp_*.py
 tmp_*.sh
 
 # Experimental/abandoned features (not part of main project)
-cloud-relay/
 scripts/agent/
 docs/internal/
 claude.md

docs/operations/audit-log-rotation.md

@@ -0,0 +1,61 @@
+# Pulse Sensor Proxy Audit Log Rotation
+
+The sensor proxy writes a tamper-evident audit trail to
+`/var/log/pulse/sensor-proxy/audit.log`. Every entry includes the SHA-256 hash
+of the previous entry, so any modification becomes obvious. Because the process
+keeps the file open and maintains the running hash in memory, rotation requires
+special handling.
+
+## Rotation Strategy
+
+Use `logrotate` to rotate the file once it reaches 100 MB. After each rotation,
+restart the proxy so it opens a new file and starts a fresh hash chain.
+
+Create `/etc/logrotate.d/pulse-sensor-proxy` with the following contents:
+
+```conf
+/var/log/pulse/sensor-proxy/audit.log {
+    daily
+    size 100M
+    rotate 90
+    compress
+    delaycompress
+    missingok
+    notifempty
+    create 0640 pulse pulse
+    sharedscripts
+    postrotate
+        systemctl restart pulse-sensor-proxy.service >/dev/null 2>&1 || true
+    endscript
+}
+```
+
+### Why a Restart Is Mandatory
+
+`copytruncate` and similar tricks break the chain integrity. Restarting the
+service ensures:
+
+1. The proxy releases the old file descriptor.
+2. A new hash chain starts at sequence 1 with an all-zero `prev_hash`.
+
+If the proxy is not restarted, it will continue writing to the renamed file and
+the rotation will have no effect.
+
+### Chain Continuity Across Rotations
+
+Each rotated log (`audit.log.1.gz`, `audit.log.2.gz`, …) is self-contained. To
+prove continuity between files:
+
+1. After each rotation, record the final `event_hash` from the rotated file (for
+   example, store it in the filename or a checksum manifest).
+2. When reviewing logs, verify the `prev_hash` of the first entry in the new
+   file is the zero hash, and reconcile the recorded final hash from the prior
+   file to show no entries were removed.
+
+Maintaining this “final hash ledger” allows auditors to stitch the rotated files
+together chronologically while preserving the tamper-evident guarantees.
+
+### Permissions
+
+Adjust the `create` directive to match the user and group that run the sensor
+proxy. The example assumes both user and group are `pulse`.