Restructure seqjob's my_alloc() as a trivial single-bucket case over the
shared xce_alloc_plan_iter_t/xce_host_iter_t contracts, replacing its own
inline worker-collection loop. Guard seqjob_prepare_allocation() to
maxTasks == 1, closing the fan-out gap for the parallel allocator's later
fix (Req 9.1, 4.6).
Export sched_try_alloc_on_host_() from resource.c (drop static/va_list,
plain (worker, sched, ctx) signature) so seqjob calls the real per-host
try-alloc leaf instead of a private duplicate; delete the now-dead
sched_try_alloc_on_hosts() variadic wrapper. Also wires host_iter.c into
the production scheduler_srcs list (task 2.1 only added it to testsuite).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XYdtrEWWZfKRRGED7raEYg
Rongsong Shen
b18c5f780d