Add missing variables to .env.example files

- Added STACKS_DIR to dashboards/.env.example (needed for homepage volume mount)
- Added HOMEPAGE_VAR_TITLE to dashboards/.env.example
- Added CODE_SERVER_PASSWORD and CODE_SERVER_SUDO_PASSWORD to infrastructure/.env.example

These variables are required by the docker-compose files but were missing from the .env.example files, causing Docker Compose to fail with 'variable is not set' errors.

docker-compose/infrastructure/.env.example

@@ -9,5 +9,9 @@ TZ=America/New_York
 # Pi-hole Configuration
 PIHOLE_WEBPASSWORD=changeme
 
+# Code Server Configuration
+CODE_SERVER_PASSWORD=changeme
+CODE_SERVER_SUDO_PASSWORD=changeme
+
 # Directory Configuration
 STACKS_DIR=/opt/stacks