refactor(codeql_compose): extract breakpoint recovery from _arun

The ~600-line _arun god function inlined a ~200-line breakpoint-recovery
block (empty-result -> synthesize isAdditionalFlowStep conditions -> re-run).
Move it verbatim into a new _recover_breakpoints method; the guard condition
stays in _arun and the four mutated locals (current_ql, exec_result,
is_result_empty, paths_count) are threaded in and returned out.

Pure extract-method: the moved body was verified line-for-line identical to
the original modulo a 16-space dedent (198/198 lines, 0 mismatches). _arun is
~184 lines shorter. compileall + ruff clean, 89 tests green.

Author: bx33661