docs: fix capitalization losses + one text corruption from the contractions pass

Review pass on top of the previous commit (85a94671) turned up three
real issues its own vale-only verification didn't catch:

- 'has not' -> 'hasn't' fired inside 'has nothing', corrupting
  docs/swarm/README.md into 'hasn'thing to say upward'. Restored
  'has nothing'.
- ~44 hits where the original text was genuinely sentence-initial
  ('It is', 'That is', 'They are', 'What is', 'Do not', ...) got
  contracted in lowercase, silently de-capitalizing the start of a
  sentence. Checked each one's real surrounding text and capitalized
  the ones that needed it.
- Confirmed (by reading the actual text, not just trusting vale) that
  the 3 remaining 'is not'/'has not'/'it is' hits after those fixes are
  vale's own false positives: it matches these as a bare substring with
  no trailing word boundary, so it also fires on 'is nothing', 'has
  nothing', and the already-correct 'it isn't'. Left those alone --
  there's no real issue in the text.

Re-verified with a fresh vale run: the remaining 17 hits are exactly
the union of the 14 legitimate ALL-CAPS/bold-emphasis skips from the
first commit and these 3 false positives. Full accounting in
/agents/iris/state/haiku-batches/contractions-report.md.

docs/scheduler/coordinator.md

@@ -100,7 +100,7 @@ container build:
   `DeployWindow` — the deploy subtree's root, which holds it across every
   phase below it (it declares `Resource::MetaWindow`). Two meta
   mutations can therefore never interleave, so no commit lands inside another
-  node's staged window. it's a queue resource rather than a runtime mutex
+  node's staged window. It's a queue resource rather than a runtime mutex
   because a resource is held by a subtree root across its whole subtree, which
   a `MutexGuard` (bounded by one executor fn) can't — that's what lets a
   multi-node deploy own one window. For the same reason the window must stay
@@ -237,7 +237,7 @@ than to one DAG shape it happens to appear in. A **brace** is the one sanctioned
 exception: a pure-resource-holder root that declares on behalf of a subtree
 coordinated with itself, whose members then declare nothing.
 
-it's forced rather than stylistic. Declaring a resource means _"I need this
+It's forced rather than stylistic. Declaring a resource means _"I need this
 exclusively"_, and the agent lease is single-unit — so **two siblings that both
 declared it could never run concurrently.** For a subtree whose whole point is
 concurrency (`Prebuild` beside the `Signal` → `Drain` quiesce window), declaring
@@ -349,7 +349,7 @@ the event's whole job.
 ## Container view
 
 `container_view.rs` maintains an in-memory snapshot of every nixos-container's
-systemd service state. it's polled on coordinator startup and re-scanned after
+systemd service state. It's polled on coordinator startup and re-scanned after
 every lifecycle operation (spawn, rebuild, kill) so the dashboard always reflects
 the actual container status without a live `nixos-container list` call on each
 render.
@@ -527,7 +527,7 @@ wants it.
 
 Two things to know about the weights:
 
-- they're **hive-wide** — unlike the caps there is no per-agent
+- They're **hive-wide** — unlike the caps there is no per-agent
   override in `meta/resource-limits.json`, so every agent carries the
   same value and the weight does _not_ rank agents against each other.
   What `80` buys is that agents yield to everything **not** on this