Migrate configuration paths to /etc/easyhaproxy and improve health check support in E2E tests

- Refactored HAProxy configuration files, templates, and paths to use `/etc/easyhaproxy` instead of `/etc/haproxy`.
- Updated Dockerfile to generate DH params and placeholder certificates in the new configuration directory.
- Added health check support with timeout to `DockerComposeFixture` in E2E test utilities.
- Adjusted tests, templates, and plugins to use the new `Consts`-based configuration paths.
- Introduced pytest fixtures for environment isolation and temporary directory management.

tests_e2e/static/conf/config-certbot.yml

@@ -15,14 +15,14 @@
 #    EASYHAPROXY_CERTBOT_EMAIL=your-email@example.com
 #
 # 4. Mount this config:
-#    -v ./conf/config-certbot.yml:/etc/haproxy/static/config.yml
+#    -v ./conf/config-certbot.yml:/etc/easyhaproxy/static/config.yml
 #
 # 5. Persist certificates:
-#    -v ./certs/certbot:/certs/certbot
+#    -v ./etc/easyhaproxy/certs/certbot:/etc/easyhaproxy/certs/certbot
 #
 # How it works:
 # - EasyHAProxy requests certificates from Let's Encrypt via HTTP-01 challenge
-# - Certificates are stored in /certs/certbot/
+# - Certificates are stored in /etc/easyhaproxy/certs/certbot/
 # - Certificates auto-renew when needed
 #
 # Note: Let's Encrypt has rate limits. Use staging environment for testing:
@@ -56,7 +56,7 @@ containers:
   # Domain without certbot (uses custom certificate)
   "custom.example.com:80":
     ip: ["custom-app:8080"]
-    # No certbot - expects certificate at /certs/haproxy/custom.example.com.pem
+    # No certbot - expects certificate at /etc/easyhaproxy/certs/haproxy/custom.example.com.pem
 
   # HTTPS Port 443
   # Serves HTTPS traffic with auto-generated certificates
@@ -65,7 +65,7 @@ containers:
     ip: ["webapp:8080"]
     ssl: true
     # Certificate path (auto-generated by certbot)
-    # /certs/certbot/example.com/fullchain.pem
+    # /etc/easyhaproxy/certs/certbot/example.com/fullchain.pem
 
   "app.example.com:443":
     ip: ["app:3000"]
@@ -76,7 +76,7 @@ containers:
     ip: ["custom-app:8080"]
     ssl: true
     # Place your certificate at:
-    # /certs/haproxy/custom.example.com.pem
+    # /etc/easyhaproxy/certs/haproxy/custom.example.com.pem
 
 # Multiple domains with different backends
 # Certbot will request separate certificates for each domain