style: ruff format after MCP server integration

Reformat the files touched by Tasks 1-14 of the host-agent MCP server
plan. No semantic changes; pre-existing format issues in unrelated
files (test_templates, test_skill_sync_wiring, 0010_skill_management,
test_skill_catalog_mcp) left untouched for a separate housekeeping
pass.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/device-host-agent/host_agent/mcp_lock.py

@@ -57,9 +57,7 @@ class McpBusyTracker:
             lease = McpDeviceLease(
                 device_id=device_id,
                 session_id=session_id,
-                acquired_at=(
-                    existing.acquired_at if existing is not None else now
-                ),
+                acquired_at=(existing.acquired_at if existing is not None else now),
                 last_seen_at=now,
             )
             self._leases[device_id] = lease
@@ -154,4 +152,4 @@ class McpBusyTracker:
             if (cutoff - lease.last_seen_at).total_seconds() > self._ttl
         ]
         for device_id in expired:
-            del self._leases[device_id]
+            del self._leases[device_id]