LOS ANGELES - A steel tower wrapped in a spiraling ribbon is one of the most striking features of a new arts high school set to open next year. Its $230 million price tag is another. The Los Angeles High School for the Visual and Performing Arts, with space for some 1,600 students, most from surrounding low-income neighborhoods, is the architectural crown jewel of the district's ambitious $20 billion building campaign. Its spacious studios and 995-seat theater encased in austere concrete are enough to make anybody wish they were a young clarinetist in the district.