feat(db): add context_text column to reading_progress

Stores surrounding text (~100 chars) at the reader's current position.
Used as fallback for CFI resolution when converting between epubcfi
and CREngine XPointer formats.

Updates:
- schema.sql: add context_text TEXT column, update stored procedure
- queries.sql: add context_text to GetUniversalProgress and
  UpdateUniversalProgress queries
- Regenerate sqlc Go code (models.go, querier.go, queries.sql.go)

internal/database/querier.go

@@ -280,6 +280,7 @@ type Querier interface {
 	// Get user reading history for analytics
 	GetUserReadingHistory(ctx context.Context, arg GetUserReadingHistoryParams) ([]GetUserReadingHistoryRow, error)
 	GetUserVisibleLibraries(ctx context.Context, userID pgtype.UUID) ([]GetUserVisibleLibrariesRow, error)
+	HasRecentConflictResolution(ctx context.Context, arg HasRecentConflictResolutionParams) (bool, error)
 	IncrementSyncQueueAttempts(ctx context.Context, arg IncrementSyncQueueAttemptsParams) (SyncQueue, error)
 	// Check if book is in collection
 	IsBookInCollection(ctx context.Context, arg IsBookInCollectionParams) (bool, error)