feat(01-01): add level-up migration with partial unique index

- Generate migration 20260427122603_add_level_up_sessions_and_class_progression
- Auto-creates LevelUpSession, LevelUpHistory, ClassProgression, ClassFeatureOption tables
- Adds Character.freeArchetype and Character.prereqViolations columns
- Hand-append partial unique index 'LevelUpSession_characterId_open_unique'
  with WHERE "committedAt" IS NULL clause (Prisma 7 cannot emit partial indexes)
- Migration applied to dev database via prisma migrate dev
- Prisma Client regenerated and exposes new models + Character columns

server/prisma/migrations/20260427122603_add_level_up_sessions_and_class_progression/migration.sql

@@ -0,0 +1,90 @@
+-- AlterTable
+ALTER TABLE "Character" ADD COLUMN     "freeArchetype" BOOLEAN NOT NULL DEFAULT false,
+ADD COLUMN     "prereqViolations" JSONB;
+
+-- CreateTable
+CREATE TABLE "LevelUpSession" (
+    "id" TEXT NOT NULL,
+    "characterId" TEXT NOT NULL,
+    "targetLevel" INTEGER NOT NULL,
+    "state" JSONB NOT NULL DEFAULT '{}',
+    "committedAt" TIMESTAMP(3),
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "LevelUpSession_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "LevelUpHistory" (
+    "id" TEXT NOT NULL,
+    "characterId" TEXT NOT NULL,
+    "levelFrom" INTEGER NOT NULL,
+    "levelTo" INTEGER NOT NULL,
+    "snapshotBefore" JSONB NOT NULL,
+    "choices" JSONB NOT NULL,
+    "committedAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "LevelUpHistory_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "ClassProgression" (
+    "id" TEXT NOT NULL,
+    "className" TEXT NOT NULL,
+    "level" INTEGER NOT NULL,
+    "grants" TEXT[],
+    "proficiencyChanges" JSONB NOT NULL,
+    "spellSlotIncrement" JSONB,
+    "cantripIncrement" INTEGER,
+    "repertoireIncrement" INTEGER,
+    "choiceType" TEXT,
+    "choiceOptionsRef" TEXT,
+
+    CONSTRAINT "ClassProgression_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "ClassFeatureOption" (
+    "id" TEXT NOT NULL,
+    "optionsRef" TEXT NOT NULL,
+    "optionKey" TEXT NOT NULL,
+    "name" TEXT NOT NULL,
+    "nameGerman" TEXT,
+    "description" TEXT NOT NULL,
+    "grants" TEXT[],
+    "proficiencyChanges" JSONB,
+
+    CONSTRAINT "ClassFeatureOption_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "LevelUpSession_characterId_idx" ON "LevelUpSession"("characterId");
+
+-- CreateIndex
+CREATE INDEX "LevelUpHistory_characterId_committedAt_idx" ON "LevelUpHistory"("characterId", "committedAt" DESC);
+
+-- CreateIndex
+CREATE INDEX "ClassProgression_className_idx" ON "ClassProgression"("className");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "ClassProgression_className_level_key" ON "ClassProgression"("className", "level");
+
+-- CreateIndex
+CREATE INDEX "ClassFeatureOption_optionsRef_idx" ON "ClassFeatureOption"("optionsRef");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "ClassFeatureOption_optionsRef_optionKey_key" ON "ClassFeatureOption"("optionsRef", "optionKey");
+
+-- AddForeignKey
+ALTER TABLE "LevelUpSession" ADD CONSTRAINT "LevelUpSession_characterId_fkey" FOREIGN KEY ("characterId") REFERENCES "Character"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "LevelUpHistory" ADD CONSTRAINT "LevelUpHistory_characterId_fkey" FOREIGN KEY ("characterId") REFERENCES "Character"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- Partial unique index: enforce at most one open DRAFT per character.
+-- Prisma 7 cannot express partial indexes via @@unique; this raw SQL is required.
+-- See: .planning/phases/01-level-up-pf2e-regelkonform/01-RESEARCH.md §Don't Hand-Roll.
+CREATE UNIQUE INDEX "LevelUpSession_characterId_open_unique"
+  ON "LevelUpSession"("characterId")
+  WHERE "committedAt" IS NULL;