Add policy, intake, and payment history to the admin student detail view

The student-administration spec deferred three detail-view sections until
Payments landed. Adds them now: policy-acceptance history (title, version,
context, date), intake answers (label, answer, context), and — gated on
manage_billing — payment history with HST breakdown and receipt numbers.

New Auth\StudentHistory builds the display rows from per-student queries
added to AcceptanceRepository, AnswerRepository, and PaymentRepository;
the Payment model now carries created_at so unpaid rows still have a date.

Closes #69

Co-Authored-By: Claude Fable 5 <[email protected]>

src/Payment/Payment.php

@@ -49,6 +49,7 @@ class Payment {
 		public readonly ?string $receiptNumber = null,
 		public readonly ?string $receiptSentAt = null,
 		public readonly ?string $paidAt = null,
+		public readonly ?string $createdAt = null,
 		public readonly ?int $id = null,
 	) {}
 
@@ -69,6 +70,7 @@ class Payment {
 			receiptNumber:         Val::stringOrNull( $row->receipt_number ),
 			receiptSentAt:         Val::stringOrNull( $row->receipt_sent_at ),
 			paidAt:                Val::stringOrNull( $row->paid_at ),
+			createdAt:             Val::stringOrNull( $row->created_at ),
 			id:                    Val::int( $row->id ),
 		);
 	}
@@ -120,6 +122,7 @@ class Payment {
 			'status'            => $this->status,
 			'receipt_number'    => $this->receiptNumber,
 			'paid_at'           => $this->paidAt,
+			'created_at'        => $this->createdAt,
 		];
 	}
 }

src/Payment/PaymentRepository.php

@@ -132,6 +132,23 @@ class PaymentRepository {
 		return $row ? Payment::fromRow( $row ) : null;
 	}
 
+	/**
+	 * Every payment for a student, newest first (admin payment history).
+	 *
+	 * @return list<Payment>
+	 */
+	public function findByStudent( int $studentId ): array {
+		$rows = $this->db->get_results(
+			$this->db->prepare(
+				'SELECT * FROM %i WHERE student_id = %d ORDER BY created_at DESC, id DESC',
+				$this->table,
+				$studentId
+			)
+		);
+
+		return array_map( Payment::fromRow( ... ), $rows ?? [] );
+	}
+
 	/**
 	 * Pending payments, newest first (studio-admin confirmation queue).
 	 *