fix(manager-core): F-P-007 concurrent queue dispatch per tick

tick_queue_arm called list_active_queue_consumers() and then iterated
serially, awaiting one queue.claim(app, queue) per consumer. With N
consumers and a 100ms tick the worst-case throughput was
N × (claim + executor) / tick — one slow handler blocked every other
queue's progress on the dispatcher's task.

Replace the for-loop with `futures::stream::iter(consumers)
.for_each_concurrent(QUEUE_DISPATCH_PARALLELISM, …)`. The execution
gate already caps real script-concurrency to its permits, so this just
removes the dispatcher-side serialization.

QUEUE_DISPATCH_PARALLELISM = 32 (matches the default gate). Workspace
gains `futures = 0.3` so `for_each_concurrent` is available.

AUDIT.md anchor: F-P-007.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Cargo.toml

@@ -53,8 +53,10 @@ chrono = { version = "0.4", features = ["serde"] }
 chrono-tz = "0.9"
 cron = "0.12"
 
-# Async traits
+# Async traits + bounded-concurrency stream utilities (queue dispatcher
+# uses `for_each_concurrent`).
 async-trait = "0.1"
+futures = "0.3"
 
 # Rhai scripting. Pinned exactly (`=1.24`) because the `internals`
 # feature surface is not semver-stable — future bumps must be deliberate.