[FEAT] Add overlay prop to Loader component for container-scoped loading state

[arturrybalskyy-dev]

📝 Description

Previously, <Loader /> used position: fixed and covered the entire viewport, blocking navigation, filters, and other UI controls during data fetching. This PR adds an overlay prop that scopes the loader to its nearest positioned parent container, allowing users to interact with the rest of the page while content is loading

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🛠️ Changes Made

• Added overlay boolean prop to Loader component
• Added .overlay-loader CSS class (position: absolute; inset: 0) in loader.scss

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✅ Checklist

• I have given the PR a well-structured title describing the domain and the specific change that was made
• I tested the changes in the browser (locally or via preview build)
• I confirmed that existing tests pass
• I added or updated unit / integration tests (if needed)
• I checked that this change doesn't introduce new console warnings or lint / formatting errors
• I updated the relevant Jira ticket with the appropriate details and status

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🚨 Potentially Breaking Changes

• No

🔍 Additional Notes

• The parent container must have position: relative for overlay to work correctly