Add clock_24h plugin: 24H Clock for Agent Zero WebUI

[jphermans]

24H Clock Plugin

Forces the Agent Zero WebUI header clock to display time in 24-hour format (HH:MM:SS) instead of the default 12-hour AM/PM.

Features

• Always-on (always_enabled: true)
• Update-proof (lives in usr/plugins/)
• Zero config
• Non-destructive (MutationObserver, no core file modifications)

Validation

• Folder name: clock_24h (matches ^[a-z0-9_]+$)
• plugin.yaml has name: clock_24h matching folder name
• LICENSE (MIT) present at repo root
• Title: 9 chars (max 50)
• Description: 149 chars (max 500)
• index.yaml: 366 bytes (max 2000)
• Thumbnail: 7.1 KB JPG (max 20 KB)
• Tags: ui, utilities (from recommended list)
• Single plugin folder added

Screenshot