feat: phase 3 — history endpoints (start, entries, complete)

backend/prisma/migrations/20260326034915_add_history_program_completed/migration.sql

@@ -0,0 +1,12 @@
+/*
+  Warnings:
+
+  - Added the required column `programId` to the `histories` table without a default value. This is not possible if the table is not empty.
+
+*/
+-- AlterTable
+ALTER TABLE "histories" ADD COLUMN     "completedAt" TIMESTAMP(3),
+ADD COLUMN     "programId" TEXT NOT NULL;
+
+-- AddForeignKey
+ALTER TABLE "histories" ADD CONSTRAINT "histories_programId_fkey" FOREIGN KEY ("programId") REFERENCES "programs"("id") ON DELETE CASCADE ON UPDATE CASCADE;