Data layer: Room entities, DAOs, database with exported schema

Milestone 2. Medication / DoseTime / DoseLog per the brief's model.
DoseLog.doseTimeId is SET_NULL (schedule edits must not erase adherence
history) while medId CASCADEs; DoseLog.amount is snapshotted at logging
time so later dose changes don't rewrite the record. Inventory decrement
is a single SQL UPDATE clamped at 0 to stay race-free under escalating
notifications. Enums stored as TEXT; schema exported to app/schemas as
the migration baseline.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/src/main/java/no/naiv/meddetsamme/data/DoseLog.kt

@@ -0,0 +1,57 @@
+package no.naiv.meddetsamme.data
+
+import androidx.room.Entity
+import androidx.room.ForeignKey
+import androidx.room.Index
+import androidx.room.PrimaryKey
+
+enum class DoseStatus { PENDING, TAKEN, SKIPPED, SNOOZED }
+
+/**
+ * One scheduled occurrence of a dose and what happened to it. Created PENDING
+ * when the reminder fires (the escalation anchor), resolved by user action.
+ *
+ * SNOOZED is a *resting* state between nags — the alarm layer treats it like
+ * PENDING (keeps nagging after the snooze interval) but the UI can distinguish
+ * "I saw it and deferred" from "never reacted".
+ *
+ * [doseTimeId] is nullable and SET_NULL on delete: editing a schedule away must
+ * not erase adherence history. [medId] CASCADE instead — deleting a med (vs.
+ * deactivating) is an explicit "forget everything" action.
+ */
+@Entity(
+    tableName = "dose_log",
+    foreignKeys = [
+        ForeignKey(
+            entity = Medication::class,
+            parentColumns = ["id"],
+            childColumns = ["medId"],
+            onDelete = ForeignKey.CASCADE,
+        ),
+        ForeignKey(
+            entity = DoseTime::class,
+            parentColumns = ["id"],
+            childColumns = ["doseTimeId"],
+            onDelete = ForeignKey.SET_NULL,
+        ),
+    ],
+    indices = [
+        Index("medId"),
+        Index("doseTimeId"),
+        // The reminder layer's hot path: "is there already a log for this occurrence?"
+        Index(value = ["doseTimeId", "scheduledAtMillis"]),
+        Index("status"),
+    ],
+)
+data class DoseLog(
+    @PrimaryKey(autoGenerate = true) val id: Long = 0,
+    val medId: Long,
+    val doseTimeId: Long?,
+    /** The occurrence this log is for (epoch millis of the scheduled local time). */
+    val scheduledAtMillis: Long,
+    /** Dose size at the time of logging — schedule edits must not rewrite history. */
+    val amount: Double,
+    val status: DoseStatus = DoseStatus.PENDING,
+    /** When the user last acted on it (Taken/Skipped/Snoozed), null while untouched. */
+    val actionedAtMillis: Long? = null,
+)