docs(sensor-proxy): comprehensive config management documentation

Adds complete documentation for the new sensor-proxy config management CLI
implemented in Phase 2. Addresses user-facing aspects of the corruption fix.

**New Documentation:**
- docs/operations/sensor-proxy-config-management.md (469 lines)
  - Complete operations runbook for config management
  - Full CLI reference with examples
  - Migration guide from inline config
  - Architecture explanation
  - Common operational tasks
  - Troubleshooting guide
  - Best practices and automation

**Updated Documentation:**
- cmd/pulse-sensor-proxy/README.md
  - Configuration Management CLI section
  - Allowed Nodes File format
  - Enhanced troubleshooting
  - Config corruption recovery

- docs/TEMPERATURE_MONITORING.md
  - Config validation failure troubleshooting
  - Configuration Management quick reference
  - Cross-links to detailed docs

- docs/TROUBLESHOOTING.md
  - Sensor proxy config validation errors
  - Comprehensive diagnosis steps
  - Automatic and manual recovery

- README.md & docs/README.md
  - Added new runbook to operations index
  - Positioned for discoverability

**Coverage:**
- Both CLI commands fully documented
- Phase 1 & Phase 2 architecture explained
- Migration path from pre-v4.31.1
- Config corruption recovery procedures
- Safe config editing practices
- Automation examples
- Troubleshooting all failure modes

**Documentation Quality:**
- Cross-linked from 5 different documents
- Clear examples for common use cases
- Target audience: system administrators
- Follows project documentation style
- Production-ready

This completes the sensor-proxy config corruption fix by providing users
with comprehensive guidance for the new config management system.

Related to Phase 2 commits 3dc073a28, 804a638ea, 131666bc1

docs/README.md

@@ -45,6 +45,7 @@ section groups related guides so you can jump straight to the material you need.
 
 ## Operations Runbooks
 
+- [operations/sensor-proxy-config-management.md](operations/sensor-proxy-config-management.md) – Safe configuration updates using the built-in CLI, migration from inline config, and troubleshooting corruption issues.
 - [operations/audit-log-rotation.md](operations/audit-log-rotation.md) – Monthly/incident log rotation procedure that preserves the hash chain and validates scheduler health afterward.
 - [operations/ADAPTIVE_POLLING_ROLLOUT.md](operations/ADAPTIVE_POLLING_ROLLOUT.md) – Rollout/rollback plan for enabling adaptive polling in staging or production.
 - [operations/auto-update.md](operations/auto-update.md) – Lifecycle of the `pulse-update` timer/service: enablement, manual trigger, rollback, and observability.