Fix addTest tip and out-of-bounds trap wording

Two small mismatches on main @ 7e1a64d.

1. The zero test tip (program_graph_test.c:726) shows addTest without arg1, but the op requires it (program_graph_patch.c:761). Following the tip fails with addTest operation is missing required attributes / expected: name, call, arg0, arg1, and expect. Every other example uses the two-arg form. Suggested tip:

   tip: add a test block in source, or zero patch --op 'addTest name="..." call="<two-arg-fn>" arg0="..." arg1="..." expect="..." type="<type>"'

   Related, a two-arg addTest against a one-arg function passes zero patch validation and zero check, and only fails in zero test ("function argument count mismatch").

2. skill-data/language.md:146 says an out-of-range index "traps with a signal exit and no output". It prints trap: index out of bounds to stderr (direct_emit.c:27, emit_elf64.c:470-476), and conformance/run.mjs:1861-1862 asserts that. Suggested wording is "an out-of-range index prints trap: index out of bounds to stderr and terminates abnormally".