[M3] Create Loki Uninstall Script

[miciav]

Description

Clean uninstall of Loki based on install method.

Files to create

• scripts/uninstall_loki.sh (new)

Features

• Detect install method from marker file
• Stop service
• Remove packages/containers
• Optionally remove data

Acceptance criteria

• Cleans up all install methods
• Prompts before data deletion
• Handles partial installs

Milestone: M3 - Loki Installation Scripts
Issue: 3.2

[miciav]

Loki uninstall script available in scripts/uninstall_loki.sh.