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

packages/core/src/types.ts

@@ -24,6 +24,19 @@ export interface User {
   createdAt: string;
 }
 
+/** A single row in the instance audit log (CHUNK #10). */
+export interface AuditLogEntry {
+  id: string;
+  /** ISO-8601 UTC timestamp of when the action occurred. */
+  at: string;
+  /** Id of the acting user, or `null` for system actions. */
+  userId: string | null;
+  /** Machine-readable action name, e.g. `user_create`, `share_grant`. */
+  action: string;
+  /** Free-form context for the action (email, targetId, perm, …). */
+  detail: Record<string, unknown>;
+}
+
 export interface Project {
   id: string;
   projectId: string;