Named counting-semaphore resources — the Dep::Resource side of the v2
model. A ResourceTable tracks per-name capacity + held counts; unconfigured
names default to capacity 1 (created lazily). try_acquire_all grants every
requested unit or none, leaving the table untouched on failure — so a node
never holds one resource while waiting for another, which is what makes the
scheduler deadlock-free without cycle detection. Duplicate names in a
request are summed; over-capacity requests can never acquire. release_all
saturates rather than underflowing. Runtime scheduler state, not persisted:
held counts are rederived from running nodes on restart. Guard objects
(RAII release, recursive re-entrancy) wrap this in a follow-up.
