reminders: add ListReminders IPC + /reminders web page

Store layer: ListReminders returns the n most recent reminders
(newest first). IPC: new MethodListReminders wired through server,
client, and lockedAPI. Web: /reminders page with table of created
time, fire time, status badge, and payload text; empty state with
prompt to ask maven for a reminder. Sidebar entry under Automation.

internal/ipc/client.go

@@ -249,6 +249,14 @@ func (c *Client) MarkReminder(ctx context.Context, id int64, status string) erro
 	return c.call(ctx, MethodMarkReminder, markReminderReq{ID: id, Status: status}, nil)
 }
 
+func (c *Client) ListReminders(ctx context.Context, n int) ([]Reminder, error) {
+	var out []Reminder
+	if err := c.call(ctx, MethodListReminders, nReq{N: n}, &out); err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 func (c *Client) RecordNudge(ctx context.Context, rule, channel, message string, ts time.Time) (int64, error) {
 	var r idResp
 	if err := c.call(ctx, MethodRecordNudge, recordNudgeReq{Rule: rule, Channel: channel, Message: message, Ts: ts}, &r); err != nil {