server: fix project_shares audit logging and add share transfer

- Fix PATCH /api/projects/:id/shares/:userId: query SELECT 1 instead of
  SELECT id (project_shares has a composite PK, no id column)
- Add audit logging to existing share grant/revoke routes
- Add POST /api/projects/:id/transfer for ownership handoff
- Remove inline admin user/audit routes from routes.ts (now in admin.ts)
- Remove unused requireAdmin import and userPatch schema from routes.ts

server/src/mapping.ts

@@ -1,6 +1,7 @@
 import type {
   AISession,
   AISessionRole,
+  AuditLogEntry,
   Board,
   Book,
   Chapter,
@@ -29,6 +30,15 @@ export interface ShareRow {
   user_id: string;
   perm: "read" | "edit";
 }
+
+/** Raw `audit` table row (CHUNK #10). */
+export interface AuditRow {
+  id: string;
+  at: string;
+  user_id: string | null;
+  action: string;
+  detail: string;
+}
 export interface ProjectRow {
   id: string;
   owner_id: string;
@@ -107,6 +117,23 @@ export function toUser(r: UserRow): User {
   };
 }
 
+/** Map a raw `audit` row to the shared `AuditLogEntry` (CHUNK #10). */
+export function toAudit(r: AuditRow): AuditLogEntry {
+  let detail: Record<string, unknown> = {};
+  try {
+    detail = JSON.parse(r.detail ?? "{}") as Record<string, unknown>;
+  } catch {
+    detail = {};
+  }
+  return {
+    id: r.id,
+    at: r.at,
+    userId: r.user_id,
+    action: r.action,
+    detail,
+  };
+}
+
 export function toProject(r: ProjectRow, shares: ShareRow[]): Project {
   return {
     id: r.id,