docs: fix 329 Microsoft.Contractions hits with proper safety checks

Apply contraction fixes across ~40 doc files (setup, integrations, lifecycle,
networking, scheduler, swarm, tools, trust-boundary, UI, etc.). Skipped 14 hits:
- 10 where words appear in ALL CAPS for deliberate emphasis (is NOT, do NOT, etc.)
- 4 where text could not be safely located due to markdown formatting or column position

Applied via systematic scan with checks for fenced code blocks, inline code spans,
and intentional caps. Preserves sentence-initial capitalization throughout.

docs/agent-lifecycle/agent-hierarchy.md

@@ -127,7 +127,7 @@ other agents don't:
   equivalent on their own socket.
 - **Storage/mounts** — only the manager container gets
   `/var/lib/hyperhive/agents` bind-mounted RW at `/agents` (so it can
-  manage any agent's state dir — config is not authored there, since a
+  manage any agent's state dir — config isn't authored there, since a
   real config change is a PR from a clone), plus RO mounts for
   `/applied` (diff against what's deployed) and `/meta` (system-wide
   deploy log). Planned: each agent gets RW to `/agents/<descendant>/`