feat(schema): make note_id and is_reversed NOT NULL

All cards now require note association - legacy card support removed.
This aligns with the note-based card architecture introduced in Phase 8.

- Add database migration for NOT NULL constraints
- Update client Dexie schema to version 3
- Remove LegacyCardItem component and legacy card handling
- Update sync schemas and type definitions
- Update all tests to use note-based cards

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/src/client/sync/pull.ts b/src/client/sync/pull.ts
index 55c859c..8b55a9b 100644
--- a/src/client/sync/pull.ts
+++ b/src/client/sync/pull.ts
@@ -33,8 +33,8 @@ export interface ServerDeck {
 export interface ServerCard {
 	id: string;
 	deckId: string;
-	noteId?: string | null;
-	isReversed?: boolean | null;
+	noteId: string;
+	isReversed: boolean;
 	front: string;
 	back: string;
 	state: number;
@@ -172,8 +172,8 @@ function serverCardToLocal(card: ServerCard): LocalCard {
 	return {
 		id: card.id,
 		deckId: card.deckId,
-		noteId: card.noteId ?? null,
-		isReversed: card.isReversed ?? null,
+		noteId: card.noteId,
+		isReversed: card.isReversed,
 		front: card.front,
 		back: card.back,
 		state: card.state as CardStateType,