Publish path, no dispatch -- FABRIC-3.6.md task 3.3

sk_hermes_publish() allocates one SkHermesMessage per channel member
(heat-cost ruling 2026-09-21: one message per subscriber, funded by
the publisher's own reservoir) and enqueues each onto a new
per-subscriber SkHermesPendingQueue -- found-or-created lazily by
vm_id, sized from stadium_max_vm_count() like the channel/switch
tables. Best-effort across subscribers: a failed allocation or full
queue skips and rolls back just that one subscriber, not the whole
publish -- the natural reading of "ledger and stadium_conserved() hold
across N publishes to M subscribers" (the task's own check), not a
separate ruling.

Dispatches nothing -- sk_hermes_pending_count()/peek()/pop() are the
read/drain primitives task 3.4's real checkpoint-driven drain will
build on; this task's own self-test uses them directly since no
checkpoint hook exists yet.

Verified live on all three architectures: pending-queue table sized
50/202/50 slots (tracking the channel table's own per-arch sizing), a
synthetic publish self-test (2 publishes to 3 subscribers) confirms
exact per-subscriber delivery counts, and ledger/stadium_conserved()
invariants hold both mid-publish and after manually draining every
queue back to baseline.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

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