Feat(policy): Add PDF upload capability to Policy Manager

[Br0wnHammer]

Describe your changes

• Add PolicyAttachments component for attaching PDF files to policies using existing FileManagerUploadModal and FilePickerModal
• Integrate PDF attachments into PolicyEditorPage (visible for existing policies, below metadata form)
• Fix file_entity_links unique constraint to include organization_id, aligning with the ON CONFLICT clause in file.repository.ts

Please ensure all items are checked off before requesting a review:

• I deployed the code locally.
• I have performed a self-review of my code.
• I have included the issue # in the PR.
• I have labelled the PR correctly.
• The issue I am working on is assigned to me.
• I have avoided using hardcoded values to ensure scalability and maintain consistency across the application.
• I have ensured that font sizes, color choices, and other UI elements are referenced from the theme.
• My pull request is focused and addresses a single, specific feature.
• If there are UI changes, I have attached a screenshot or video to this PR.