Add visit placement on care units and beds.

Patients can be admitted, transferred, and discharged from unit/bed stays with occupancy sync, so MAR and ward boards have inpatient context.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/Models/Bed.php

@@ -5,6 +5,8 @@ namespace App\Models;
 use App\Models\Concerns\BelongsToOwner;
 use Illuminate\Database\Eloquent\Model;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Illuminate\Database\Eloquent\Relations\HasMany;
+use Illuminate\Database\Eloquent\Relations\HasOne;
 use Illuminate\Database\Eloquent\SoftDeletes;
 
 class Bed extends Model
@@ -41,4 +43,18 @@ class Bed extends Model
     {
         return $this->belongsTo(CareUnit::class, 'care_unit_id');
     }
+
+    public function stays(): HasMany
+    {
+        return $this->hasMany(BedStay::class, 'bed_id');
+    }
+
+    public function activeStay(): HasOne
+    {
+        return $this->hasOne(BedStay::class, 'bed_id')
+            ->ofMany(
+                ['id' => 'max'],
+                fn ($query) => $query->where('status', BedStay::STATUS_ACTIVE),
+            );
+    }
 }