Add HAProxy monitoring dashboard features

- Introduced a new `dashboard` frontend in HAProxy configuration to serve a real-time monitoring dashboard.
- Added support for returning prebuilt `dashboard.html` for `/` or `/index.html` paths.
- Updated test cases and expected outputs to accommodate the new frontend.

tests/conftest.py

@@ -16,20 +16,46 @@ _test_session_dir = tempfile.mkdtemp(prefix="pytest_easyhaproxy_")
 os.environ["EASYHAPROXY_BASE_PATH"] = _test_session_dir
 
 
+_CONTAINER_ENV_VARS = [
+    "HAPROXY_USERNAME",
+    "HAPROXY_PASSWORD",
+    "HAPROXY_STATS_PORT",
+    "HAPROXY_STATS_CORS_ORIGIN",
+    "HAPROXY_CUSTOMERRORS",
+    "EASYHAPROXY_SSL_MODE",
+    "EASYHAPROXY_LABEL_PREFIX",
+    "EASYHAPROXY_LOG_LEVEL",
+    "HAPROXY_LOG_LEVEL",
+    "CERTBOT_LOG_LEVEL",
+    "EASYHAPROXY_CERTBOT_EMAIL",
+    "EASYHAPROXY_CERTBOT_SERVER",
+    "EASYHAPROXY_CERTBOT_AUTOCONFIG",
+    "EASYHAPROXY_CERTBOT_EAB_KID",
+    "EASYHAPROXY_CERTBOT_EAB_HMAC_KEY",
+    "EASYHAPROXY_PLUGINS_ENABLED",
+    "EASYHAPROXY_PLUGINS_ABORT_ON_ERROR",
+]
+
+
 @pytest.fixture(scope="function", autouse=True)
 def reset_consts():
     """
-    Reset Consts before and after each test.
+    Reset Consts and ContainerEnv environment variables before and after each test.
 
     This ensures:
     1. Each test picks up the EASYHAPROXY_BASE_PATH environment variable
     2. Tests don't get permission errors trying to write to /etc/easyhaproxy/
     3. Consts path cache is cleared between tests for isolation
+    4. Environment variables set by ContainerEnv._yaml_to_env don't bleed across tests
     """
     from functions import Consts
     Consts.reset()
+    for var in _CONTAINER_ENV_VARS:
+        os.environ.pop(var, None)
     yield
     Consts.reset()
+    for var in _CONTAINER_ENV_VARS:
+        os.environ.pop(var, None)
 
 
 def pytest_sessionfinish(session, exitstatus):

tests/expected/docker.txt

@@ -37,6 +37,14 @@ backend srv_stats
     mode http
     server Local 127.0.0.1:1936
 
+frontend dashboard
+    bind *:11936
+    mode http
+    acl is_index path /
+    acl is_index path /index.html
+    http-request return status 200 content-type "text/html" file /etc/easyhaproxy/www/dashboard.html if is_index
+    http-request return status 404
+
 frontend http_in_443
     bind *:443  ssl crt /etc/easyhaproxy/certs/certbot/ alpn h2,http/1.1 crt /etc/easyhaproxy/certs/haproxy/ alpn h2,http/1.1
     mode http

tests/expected/services-letsencrypt.txt

@@ -45,6 +45,14 @@ backend srv_stats
     mode http
     server Local 127.0.0.1:1936
 
+frontend dashboard
+    bind *:11936
+    mode http
+    acl is_index path /
+    acl is_index path /index.html
+    http-request return status 200 content-type "text/html" file /etc/easyhaproxy/www/dashboard.html if is_index
+    http-request return status 404
+
 frontend http_in_80
     bind *:80
     mode http

tests/expected/services-multiple-hosts.txt

@@ -45,6 +45,14 @@ backend srv_stats
     mode http
     server Local 127.0.0.1:1937
 
+frontend dashboard
+    bind *:11937
+    mode http
+    acl is_index path /
+    acl is_index path /index.html
+    http-request return status 200 content-type "text/html" file /etc/easyhaproxy/www/dashboard.html if is_index
+    http-request return status 404
+
 frontend http_in_19901
     bind *:19901
     mode http

tests/expected/ssl-loose.txt

@@ -35,6 +35,14 @@ backend srv_stats
     mode http
     server Local 127.0.0.1:1936
 
+frontend dashboard
+    bind *:11936
+    mode http
+    acl is_index path /
+    acl is_index path /index.html
+    http-request return status 200 content-type "text/html" file /etc/easyhaproxy/www/dashboard.html if is_index
+    http-request return status 404
+
 backend certbot_backend
     mode http
     server certbot 127.0.0.1:2080

tests/expected/static-cors.txt

@@ -52,6 +52,14 @@ backend srv_stats
     mode http
     server Local 127.0.0.1:1936
 
+frontend dashboard
+    bind *:11936
+    mode http
+    acl is_index path /
+    acl is_index path /index.html
+    http-request return status 200 content-type "text/html" file /etc/easyhaproxy/www/dashboard.html if is_index
+    http-request return status 404
+
 frontend http_in_80
     bind *:80
     mode http

tests/expected/static.txt

@@ -45,6 +45,14 @@ backend srv_stats
     mode http
     server Local 127.0.0.1:1936
 
+frontend dashboard
+    bind *:11936
+    mode http
+    acl is_index path /
+    acl is_index path /index.html
+    http-request return status 200 content-type "text/html" file /etc/easyhaproxy/www/dashboard.html if is_index
+    http-request return status 404
+
 frontend http_in_443
     bind *:443  ssl crt /etc/easyhaproxy/certs/certbot/ alpn h2,http/1.1 crt /etc/easyhaproxy/certs/haproxy/ alpn h2,http/1.1
     mode http