Email inboxes, GitHub sources, and the first content calendar

This period expanded the product in several visible directions.

What changed

• It became possible to use email inboxes as a receive-only source for forwarded newsletters, articles, and notes.
• The Sources page was reorganized around folders, folder-level bulk actions, unhandled-item filters, and clearer counts.
• GitHub repositories became available as a source type, with their items flowing into the shared Items view.
• Summon Ideas, goals, and idea portals expanded the Ideas workflow.
• Content variants and regeneration became available on the Review page.
• The app got a real content calendar and a posting-activity heatmap.

Availability notes

• Email and GitHub only mattered if those source types were connected.
• Email inboxes were still receive-only and still depended on forwarding-based setup for some use cases.