Move device classification app lists to YAML configuration

[NotYuSheng]

Problem

DeviceClassifierService.java contains four hardcoded Set<String> collections used to classify devices by the nDPI application names observed in their traffic:

• MOBILE_APPS — 13 entries (Instagram, TikTok, WhatsApp, etc.)
• DESKTOP_APPS — 18 entries (Zoom, Teams, Steam, SSH, etc.)
• SERVER_APPS — 12 entries (PostgreSQL, MySQL, Redis, Kafka, etc.)
• IOT_CATEGORIES — 2 entries (IoT-Scada, Cloud)

Any new nDPI application that should influence device classification (e.g. a new messaging app) requires a Java recompile and redeployment.

Proposed Solution

Move these lists to a dedicated YAML configuration file loaded by Spring's @ConfigurationProperties. This makes classification rules configurable without touching Java code.

Example config (application.yml or dedicated device-classification.yml):

device-classification:
  mobile-apps:
    - Instagram
    - TikTok
    - Snapchat
    - WhatsApp
    - WeChat
    - Line
    - Viber
    - Telegram
    - Signal
    - iMessage
    - FaceTime
    - AirDrop
    - Siri
  desktop-apps:
    - Zoom
    - Teams
    - Slack
    - Discord
    - Skype
    - WebEx
    - GoToMeeting
    - BitTorrent
    - Steam
    - Battle.net
    - League of Legends
    - Valorant
    - Remote Desktop
    - SSH
    - SMB
    - NFS
    - VNC
    - TeamViewer
  server-apps:
    - PostgreSQL
    - MySQL
    - MongoDB
    - Redis
    - Elasticsearch
    - Kafka
    - RabbitMQ
    - Memcached
    - LDAP
    - Kerberos
    - SNMP
    - Syslog
  iot-categories:
    - IoT-Scada
    - Cloud

Implementation

@ConfigurationProperties(prefix = "device-classification")
@Component
public class DeviceClassificationProperties {
    private Set<String> mobileApps = new HashSet<>();
    private Set<String> desktopApps = new HashSet<>();
    private Set<String> serverApps = new HashSet<>();
    private Set<String> iotCategories = new HashSet<>();
    // getters/setters
}

Inject DeviceClassificationProperties into DeviceClassifierService and replace the static Set references.

Files to Change

• backend/src/main/java/com/tracepcap/analysis/service/DeviceClassifierService.java
• backend/src/main/resources/application.yml (or new device-classification.yml)
• New DeviceClassificationProperties.java config class

Acceptance Criteria

• MOBILE_APPS, DESKTOP_APPS, SERVER_APPS, IOT_CATEGORIES static sets removed from Java
• Lists loaded from YAML via @ConfigurationProperties
• Adding a new app to classification requires only a YAML change (no recompile)
• Existing classification behaviour is unchanged