Add Label Management

[mileswhiteford]

Summary:

• Add ManageLabels Azure Function with CRUD operations for label definitions (stored in labels/label_library.json blob)
• Add Label Management Streamlit page with tabs for viewing, adding, and editing labels
• Labels are stored with name, description, and metadata for future use by AI segment labeling

New Files:

• ManageLabels/init.py — HTTP-triggered function supporting GET, POST, PUT, DELETE
• ManageLabels/function.json — Function trigger configuration
• ui/pages/1_Label_Management.py — Streamlit UI with View/Add/Edit tabs

Environment Setup

• Add MANAGE_LABELS_URL to ui/.env with the ManageLabels function URL and key