fix(homeassistant): storage reads used of total with its percentage, and an OS update is said to wait on a reboot (#6753, #6754)

The tile shows Home Assistant's own used figure beside the total, so it matches
Home Assistant's storage page. An OS update doesn't reboot the machine: Supervisor
writes the image, reports the new version and raises a repair asking for a reboot.
The confirmation, schedule warning, MCP docs and plugin docs now say so.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

plugins/homeassistant/service.py

@@ -141,8 +141,10 @@ def read_health(found: dict) -> dict:
             problems.append({"kind": "supervisor", "severity": "error" if word == "unhealthy" else "warning",
                              "title": f"The Supervisor calls this system {word}: {str(reason).replace('_', ' ')}."})
     host = found.get("host") or {}
-    free, total = host.get("disk_free"), host.get("disk_total")
+    free, used, total = host.get("disk_free"), host.get("disk_used"), host.get("disk_total")
     free_pct = round(100 * free / total, 1) if free is not None and total else None
+    # Used and free don't add up to the total: the system reserves some of the disk.
+    used_pct = round(100 * used / total, 1) if used is not None and total else None
     if free_pct is not None and free_pct < LOW_DISK_PCT:
         problems.append({"kind": "disk", "severity": "error", "title": f"Only {free:g} GB of {total:g} GB free."})
     boots = found.get("boots") or {}
@@ -151,7 +153,8 @@ def read_health(found: dict) -> dict:
             problems.append({"kind": "addon", "severity": "error",
                              "title": f"{addon.get('name') or addon.get('slug')} should start on its own and isn't running."})
     return {"repairs_read": issues is not None, "supervised": found.get("resolution") is not None, "problems": problems,
-            "disk_free_gb": free, "disk_total_gb": total, "disk_free_pct": free_pct}
+            "disk_free_gb": free, "disk_used_gb": used, "disk_total_gb": total,
+            "disk_free_pct": free_pct, "disk_used_pct": used_pct}
 
 
 def problems_open(health: dict | None) -> list[dict]: