feat(db): mesh data model — meshes, members, invites, audit log

- pgSchema "mesh" with 4 tables isolating the peer mesh domain
- Enums: visibility, transport, tier, role
- audit_log is metadata-only (E2E encryption enforced at broker/client)
- Cascade on mesh delete, soft-delete via archivedAt/revokedAt

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/db/src/schema/chat.ts

@@ -0,0 +1,73 @@
+import { relations } from "drizzle-orm";
+import { integer, jsonb, pgSchema, timestamp, text } from "drizzle-orm/pg-core";
+
+import { generateId } from "@turbostarter/shared/utils";
+
+import { createInsertSchema, createSelectSchema } from "../utils/drizzle-zod";
+
+import { user } from "./auth";
+
+export const schema = pgSchema("chat");
+
+export const messageRoleEnum = schema.enum("role", [
+  "system",
+  "assistant",
+  "user",
+]);
+
+export const chat = schema.table("chat", {
+  id: text().primaryKey().notNull().$defaultFn(generateId),
+  name: text(),
+  userId: text()
+    .references(() => user.id, {
+      onDelete: "cascade",
+      onUpdate: "cascade",
+    })
+    .notNull(),
+  createdAt: timestamp().defaultNow(),
+});
+
+export const message = schema.table("message", {
+  id: text().primaryKey().notNull().$defaultFn(generateId),
+  chatId: text()
+    .references(() => chat.id, { onDelete: "cascade", onUpdate: "cascade" })
+    .notNull(),
+  role: messageRoleEnum().notNull(),
+  createdAt: timestamp().defaultNow(),
+});
+
+export const messageRelations = relations(message, ({ many }) => ({
+  part: many(part),
+}));
+
+export const part = schema.table("part", {
+  id: text().primaryKey().notNull().$defaultFn(generateId),
+  messageId: text()
+    .references(() => message.id, { onDelete: "cascade", onUpdate: "cascade" })
+    .notNull(),
+  type: text().notNull(),
+  order: integer().notNull(),
+  details: jsonb().notNull(),
+  createdAt: timestamp().defaultNow(),
+});
+
+export const partRelations = relations(part, ({ one }) => ({
+  message: one(message, {
+    fields: [part.messageId],
+    references: [message.id],
+  }),
+}));
+
+export const selectChatSchema = createSelectSchema(chat);
+export const insertChatSchema = createInsertSchema(chat);
+export const selectMessageSchema = createSelectSchema(message);
+export const insertMessageSchema = createInsertSchema(message);
+export const selectPartSchema = createSelectSchema(part);
+export const insertPartSchema = createInsertSchema(part);
+
+export type SelectChat = typeof chat.$inferSelect;
+export type InsertChat = typeof chat.$inferInsert;
+export type SelectMessage = typeof message.$inferSelect;
+export type InsertMessage = typeof message.$inferInsert;
+export type SelectPart = typeof part.$inferSelect;
+export type InsertPart = typeof part.$inferInsert;