Fix remote Transmission detection and config directory creation

- Fix bug where installer doesn't ask if Transmission is remote
- Fix missing configuration directory in /etc/transmission-rss-manager
- Create symlink between config locations to ensure app always finds config
- Ensure CONFIG_DIR is properly exported in the environment
- Update version to 2.0.4

🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>

main-installer.sh

@@ -146,6 +146,8 @@ else
   
   # Step 3: Create installation directories
   log "INFO" "Creating directories..."
+  # Make sure CONFIG_DIR is set and exported
+  export CONFIG_DIR=${CONFIG_DIR:-"/etc/transmission-rss-manager"}
   create_directories || {
     log "ERROR" "Directory creation failed"
     exit 1