Users were abandoning Pulse due to catastrophic temperature monitoring setup failures. This commit addresses the root causes:
**Problem 1: Silent Failures**
- Installations reported "SUCCESS" even when proxy never started
- UI showed green checkmarks with no temperature data
- Zero feedback when things went wrong
**Problem 2: Missing Diagnostics**
- Service failures logged only in journald
- Users saw "Something going on with the proxy" with no actionable guidance
- No way to troubleshoot from error messages
**Problem 3: Standalone Node Issues**
- Proxy daemon logged continuous pvecm errors as warnings
- "ipcc_send_rec" and "Unknown error -1" messages confused users
- These are expected for non-clustered/LXC setups
**Solutions Implemented:**
1. **Health Gate in install.sh (lines 1588-1629)**
- Verify service is running after installation
- Check socket exists on host
- Confirm socket visible inside container via bind mount
- Fail loudly with specific diagnostics if any check fails
2. **Actionable Error Messages in install-sensor-proxy.sh (lines 822-877)**
- When service fails to start: dump full systemctl status + 40 lines of logs
- When socket missing: show permissions, service status, and remediation command
- Include common issues checklist (missing user, permission errors, lm-sensors, etc.)
- Direct link to troubleshooting docs
3. **Better Standalone Node Detection in ssh.go (lines 585-595)**
- Recognize "Unknown error -1" and "Unable to load access control list" as LXC indicators
- Log at INFO level (not WARN) since this is expected behavior
- Clarify message: "using localhost for temperature collection"
**Impact:**
- Eliminates "green checkmark but no temps" scenario
- Users get immediate actionable feedback on failures
- Standalone/LXC installations work silently without error spam
- Reduces support burden from #571 (15+ comments of user frustration)
Related to #571