fix(app): adjust scroll and padding

[benforshey]

The original bug that prompted this probably had to do something with the Document Panel's positioning being too far down the page, which has been fixed in another PR. This PR adds some padding to the bottom of the Document Panel and prevents scroll chaining so that users can freely scroll any overflow content in the panel without scrolling the rest of the page.

[benforshey]

To test this, please verify

• that the app's test pass
• any scrollable cards in the Document Panel can clear the bottom of the Form Actions bar, so that user could clearly see there is no additional content behind / below the Form Actions bar
• scrolling to the bottom of the Document Panel (when filled with scrollable cards) does not scroll chain the document

This query helped me find a document with enough comments to be scrollable: db.Comments.aggregate([{ $group: { _id: "$documentId", count: { $sum: 1 } } }, { $sort: { count: -1 } }]).