0.26.0 - qti import / qti export on the command line

[0.26.0] - 2026-09-16

qti import / qti export on the command line (engine#164)

The QTI adapter was reachable only from code. learn-content-engine qti import <file.xml> [--out <lesson.json>] [--id] [--title] maps a 2.x or 3.0
item or test (dialect detected) to lesson JSON, on stdout or into a file;
qti export <lesson.json> [--out <file.xml>] [--version 2.x|3.0] goes the
other way. Exit codes as for every subcommand: 0 converted, 1 refused with
every unmappable item or exercise listed on stderr, 2 usage. The core
(src/qti-command.ts) is filesystem-free and pinned by the bin-shim
contract test; the bin shim owns the I/O. The comparative analysis names
interchange as the engine's entry door for content that lives in QTI; this
turns it into a two-minute try.