Typst 0.15: angle.l/angle.r symbols rejected; use chevron.l/chevron.r

When reproducing handouts in Typst 0.15.x, sym.angle.l and angle.r (as used for sequence brackets like ⟨a, b, c⟩) were rejected by the compiler. chevron.l and chevron.r work. Related, from the same batch of handout transcriptions: wrap tokens like $i$th in a box (box[$i$th]) to stop a line break between the math and the suffix, and number list items by hand (2.) when an #hrule or paragraph sits between items, because + restarts at 1. Fanning lab-to-Typst transcription out to 3 parallel agents (about 3 labs each, a shared model file, compile plus a visual PNG check) took about 2-3 minutes per batch.