Renames locals/params that shadowed base-class properties (Node.name,
Control.size, BoxContainer.alignment), prefixes an intentionally-unused
parameter, and annotates a deliberate integer division so the console
stays clean during development.
Adds a full flashcards system: FSRS-based scheduling, cloze/basic
card types, CSV import/export, media storage, and study UI, wired
into navigation and the dashboard alongside existing question flows.