fix: complete datetime boundary and microsecond consistency

src/Phaseolies/Database/Entity/Casts/Handlers/DateTimeCast.php

@@ -51,7 +51,13 @@ public function set(mixed $value): mixed
         }
 
         if ($value instanceof DateTimeInterface) {
-            return $value->format($this->format);
+            $formatted = $value->format($this->format);
+
+            if ($this->format === 'Y-m-d H:i:s' && $value->format('u') !== '000000') {
+                return $formatted . '.' . $value->format('u');
+            }
+
+            return $formatted;
         }
 
         return $value;

src/Phaseolies/Database/Entity/Query/InteractsWithTimeframe.php

@@ -349,8 +349,8 @@ public function whereDateBetween(string $column, $start, $end): self
      */
     public function whereDateTimeBetween(string $column, $start, $end): self
     {
-        $start = $this->formatDateTime($start, true);
-        $end = $this->formatDateTime($end, true);
+        $start = $this->formatDateTime($start, 'start');
+        $end = $this->formatDateTime($end, 'end');
 
         return $this->whereBetween($column, [$start, $end]);
     }

tests/Builder/TimeframeOrConditionsTest.php

@@ -306,6 +306,26 @@ public function testFormatDateTimeWithDateTimeInterface()
         $this->assertEquals('2024-03-20 15:45:00', $b->formatDateTime($dt));
     }
 
+    public function testWhereDateTimeBetweenUsesStartAndEndOfDayForDateStrings(): void
+    {
+        $builder = $this->builder();
+
+        $builder->whereDateTimeBetween('created_at', '2024-03-20', '2024-03-21');
+
+        $property = (new \ReflectionClass(Builder::class))->getProperty('conditions');
+
+        $this->assertSame([
+            [
+                'AND',
+                'created_at',
+                'BETWEEN',
+                '2024-03-20 00:00:00',
+                '2024-03-21 23:59:59',
+                'AND',
+            ],
+        ], $property->getValue($builder));
+    }
+
     public function testFormatDateTimePreservesMicroseconds(): void
     {
         $b = $this->builder();

tests/Model/CastSystemTest.php

@@ -497,6 +497,14 @@ public function testCustomDateTimeFormatCast(): void
         $this->assertSame('2024-06-15', $model->invoiced_at->format('Y-m-d'));
     }
 
+    public function testDateTimeCastSetPreservesNonZeroMicroseconds(): void
+    {
+        $handler = CastManager::resolve('datetime');
+        $value = Carbon::createFromFormat('Y-m-d H:i:s.u', '2024-06-15 09:30:00.123456');
+
+        $this->assertSame('2024-06-15 09:30:00.123456', $handler->set($value));
+    }
+
     public function testDateTimeCastNullPassthrough(): void
     {
         $model = new MockDateCastModel(['published_at' => null]);