Initial commit: Maskarr - Tracker proxy for *arr apps

- HTTP proxy server to modify User-Agent and headers for private trackers
  - Web UI with collapsible tracker cards and real-time validation
  - Multi-tracker support with persistent JSON configuration
  - Thread-safe configuration management
  - Full HTTP methods support (GET, POST, PUT, DELETE, PATCH, HEAD, OPTIONS)
  - REST API for tracker management
  - Docker support with multi-architecture builds (amd64, arm64, arm/v7)
  - CI/CD workflows for GitHub Actions and Gitea Actions
  - Automatic publishing to GitHub Container Registry and Gitea Registry

.env.example

@@ -0,0 +1,15 @@
+# Maskarr Docker Environment Configuration
+
+# Port to expose the service
+PORT=8888
+
+# Timezone (optional)
+TZ=Europe/Madrid
+
+# Config file path inside container
+CONFIG_PATH=/app/config/maskarr_config.json
+
+# User/Group ID for running the container (optional)
+# Uncomment to match your host user
+# PUID=1000
+# PGID=1000