988 External Health Check Duplication Fix Dfde631d

# External Health Check Duplication Fix

**Fixed in version:** 0.229.019

## Issue Description

A bug was identified in the admin settings interface where the "External Health Check" configuration section was appearing twice in the "Other" tab. This created a confusing user experience with duplicate UI elements for the same functionality.

## Root Cause

The issue was located in `/application/single_app/templates/admin_settings.html` where an External Health Check section was accidentally nested inside another External Health Check section, creating a duplication in the rendered UI.

**Problem code structure:**
```html
<div class="card mb-3 p-3">
    <h5>External Health Check</h5>
    <!-- First section content -->
    <div class="card mb-3 p-3">
        <h5>External Health Check</h5>
        <!-- Duplicate section content -->
    </div>
</div>
```

## Technical Details

### Files Modified
- `/application/single_app/templates/admin_settings.html` - Removed duplicate External Health Check section
- `/application/single_app/config.py` - Updated version to 0.229.015

### Code Changes Summary
- Removed the inner nested External Health Check card section (lines 2589-2607)
- Kept the outer External Health Check section with proper structure and tooltip
- Maintained all functionality while eliminating the duplicate UI elements

## Solution Implementation

The fix involved:

1. **Identifying the duplication**: Located two identical External Health Check sections in the admin settings template
2. **Removing the inner duplicate**: Eliminated the nested card section while preserving the outer one
3. **Preserving functionality**: Ensured all form elements and functionality remained intact
4. **Version update**: Incremented version number according to project conventions

## Validation

### Test Results
A comprehensive functional test was created (`test_external_health_check_duplication_fix.py`) that validates:

- ✅ Only one "External Health Check" header exists
- ✅ Only one `enable_external_healthcheck` input field exists  
- ✅ No nested duplicate sections remain
- ✅ UI structure integrity is maintained
- ✅ All required form elements are present

### User Experience Improvements
- **Before**: Users saw two identical External Health Check sections in the Other tab
- **After**: Users see only one External Health Check section with clean, non-duplicated interface

## Impact Analysis

- **Scope**: Admin settings interface
- **Users Affected**: System administrators configuring health check endpoints
- **Risk Level**: Low (UI fix only, no functional changes)
- **Backward Compatibility**: Full compatibility maintained

## Testing Approach

The fix includes automated validation that:
1. Counts HTML elements to ensure no duplication
2. Verifies proper form structure and required elements
3. Checks for nested card structures that could indicate future duplications
4. Validates overall UI integrity

This comprehensive testing ensures the fix is robust and prevents regression of similar UI duplication issues.