Improvements and Fixes

• Added a plans page where you can choose between monthly and annual plans and upgrade/downgrade.
• Add a Pay button for clients on open invoices that is much more prominent.
• Redesigned the invoice & subscription creation flows.
• Improved the dragging experience for blocks in the eSignature flow.
• Fixed a bug so that when the Billing module is disabled, clients don't have a payment methods section in Settings anymore.
• Fixed a bug with the sidebar header sections.
• Fixed a bug related to searching in the Knowledge Base module.