[Broadcast] Tag system for groups

[viganogabriele]

Parent Epic: #26

Part of: PoliNetworkOrg/telegram#120

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Implement the tag system for organizing groups in the dashboard.

Requirements

• Assign a tag number to a group of channels (e.g., tag build(deps): bump next from 15.1.7 to 15.2.3 #1 = ['channel_A', 'channel_B', 'channel_C'])
• Create, edit, and delete tags via dashboard
• Each tag has:
  • A unique number identifier
  • A name/description
  • A list of associated group IDs

Dashboard UI

• List all tags with search/filter
• Create new tag (number, name, select groups)
• Edit existing tag
• Delete tag with confirmation
• View which groups belong to a tag

API Endpoints (backend)

• • list all tags
• • create tag
• • update tag
• • delete tag
• • get groups in tag
• • list available groups (for tag creation)

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Labels: enhancement