feat: HA scheduler leadership + templated email log

HA scheduler: the job scheduler and alert evaluator hold session-scoped
PostgreSQL advisory locks on pinned pool connections — replicas scan for
due work exactly once, failover verified live with two replicas. Manual
and hook-triggered runs stay available on any replica.

Email surface: mailer renders registered templates (invitation); every
send is logged to core.email_log with status and error text. New
GET /projects/:id/emails endpoint; Members page shows an Email log card.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

packages/api-client/src/generated/models/EmailLogEntry.ts

@@ -0,0 +1,20 @@
+/* generated using openapi-typescript-codegen -- do not edit */
+/* istanbul ignore file */
+/* tslint:disable */
+/* eslint-disable */
+export type EmailLogEntry = {
+    id: string;
+    template: string;
+    to_email: string;
+    subject: string;
+    status: EmailLogEntry.status;
+    error?: string;
+    created_at: string;
+};
+export namespace EmailLogEntry {
+    export enum status {
+        SENT = 'sent',
+        FAILED = 'failed',
+    }
+}
+