feat: ✨ swap auId in JWT for individual token

note: has not been tested to ensure there are no collisions, todo

src/main/java/icu/samnyan/aqua/net/db/AquaNetSession.kt

@@ -0,0 +1,31 @@
+package icu.samnyan.aqua.net.db
+
+import jakarta.persistence.*
+import org.springframework.data.jpa.repository.JpaRepository
+import org.springframework.stereotype.Repository
+import java.io.Serializable
+import java.time.Instant
+import java.util.UUID
+
+@Entity
+@Table(name = "aqua_net_session")
+class SessionToken(
+    @Id
+    @Column(nullable = false)
+    var token: String = UUID.randomUUID().toString(),
+
+    // Token creation time
+    @Column(nullable = false)
+    var expiry: Instant = Instant.now().plusSeconds(3 * 86400),
+
+    // Linking to the AquaNetUser
+    @ManyToOne
+    @JoinColumn(name = "auId", referencedColumnName = "auId")
+    var aquaNetUser: AquaNetUser = AquaNetUser()
+) : Serializable
+
+@Repository
+interface SessionTokenRepo : JpaRepository<SessionToken, String> {
+    fun findByToken(token: String): SessionToken?
+    fun findByAquaNetUserAuId(auId: Long): List<SessionToken>
+}