Remove Pebble infrastructure and integrate self-signed certificates into standard deployment

## Major Architectural Changes

### Removed Pebble Testing Infrastructure
- Delete application/pebble-config/ directory and files
- Delete application/compose.test.yaml (Pebble Docker Compose environment)
- Delete application/share/bin/ssl-setup-local-dns.sh (Pebble-specific DNS setup)
- Remove all Pebble references from SSL generation and setup scripts

### Integrated Self-Signed Certificates into Standard Deployment
- Add infrastructure/config/templates/nginx-https-selfsigned.conf.tpl
- Update application/share/bin/ssl-generate-test-certs.sh for container-based generation
- Modify infrastructure/scripts/deploy-app.sh to support HTTPS-by-default with self-signed certificates
- Add ENABLE_HTTPS=true configuration option (default enabled)

### New Two-Phase SSL Approach
- **Phase 1 (Standard Deployment)**: HTTPS with self-signed certificates (development/testing)
- **Phase 2 (Extra Customization)**: Let's Encrypt certificates (production)

### Benefits
- HTTPS-by-default for better security posture
- Simpler testing workflow (no external ACME server needed)
- Self-signed certificates provide encryption for development
- Let's Encrypt upgrade path preserved for production use

### Technical Details
- Self-signed certificates generated inside proxy container
- nginx configuration supports both HTTP redirects and HTTPS endpoints
- Certificate paths compatible with Let's Encrypt for seamless upgrade
- Linting and validation maintained across all changes

Author: josecelano