feat(security): add database schema for security features

- Add PasswordResetToken model for password reset flow
- Add RefreshToken model for token rotation tracking
- Add AuditLog model for security event logging
- All features disabled by default via feature flags

backend/prisma/migrations/20260124152839_add_password_reset_audit_refresh_tokens/migration.sql

@@ -0,0 +1,40 @@
+-- CreateTable
+CREATE TABLE "PasswordResetToken" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "userId" TEXT NOT NULL,
+    "token" TEXT NOT NULL,
+    "expiresAt" DATETIME NOT NULL,
+    "used" BOOLEAN NOT NULL DEFAULT false,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    CONSTRAINT "PasswordResetToken_userId_fkey" FOREIGN KEY ("userId") REFERENCES "User" ("id") ON DELETE CASCADE ON UPDATE CASCADE
+);
+
+-- CreateTable
+CREATE TABLE "RefreshToken" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "userId" TEXT NOT NULL,
+    "token" TEXT NOT NULL,
+    "expiresAt" DATETIME NOT NULL,
+    "revoked" BOOLEAN NOT NULL DEFAULT false,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    CONSTRAINT "RefreshToken_userId_fkey" FOREIGN KEY ("userId") REFERENCES "User" ("id") ON DELETE CASCADE ON UPDATE CASCADE
+);
+
+-- CreateTable
+CREATE TABLE "AuditLog" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "userId" TEXT,
+    "action" TEXT NOT NULL,
+    "resource" TEXT,
+    "ipAddress" TEXT,
+    "userAgent" TEXT,
+    "details" TEXT,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    CONSTRAINT "AuditLog_userId_fkey" FOREIGN KEY ("userId") REFERENCES "User" ("id") ON DELETE SET NULL ON UPDATE CASCADE
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "PasswordResetToken_token_key" ON "PasswordResetToken"("token");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "RefreshToken_token_key" ON "RefreshToken"("token");