fix(inbox): reload mail content when switching items (+ filter refetch)

The appshell SDK useQuery only re-runs when the action changes, not the
variables — so switching mail items (same crm.mail.history action, new
threadId) never refetched and the reader kept the first thread's content
(only the subject, a direct prop, updated). Key MailReader by threadId to
remount it on switch (same pattern Messenger already uses for ThreadView).
Also force a refetch of crm.inbox.list when the filter changes, which hit
the same stale-variables bug.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/lib/inbox-api.ts

@@ -8,7 +8,7 @@
 //   query crm.inbox.list       { state? }              -> InboxItem[]
 //   cmd   crm.inbox.transition { id, state, reason? }  -> InboxItem
 
-import { useCallback, useMemo, useState } from "react";
+import { useCallback, useEffect, useMemo, useState } from "react";
 import { useAppShell, useQuery } from "@abe-kap/appshell-sdk/react";
 import { isShellConfigured } from "./appshell";
 import type { MailThread } from "./mail-api";
@@ -40,6 +40,11 @@ function useLiveInbox(state?: InboxState): InboxData {
   const showMail = !state || state === "OPEN";
   const mq = useQuery<MailThread[]>("crm.mail.list", {});
 
+  // The SDK's useQuery only refetches when the ACTION changes, not the variables — so a filter
+  // change (same action, new { state }) wouldn't reload. Force a refetch when the filter changes.
+  const refetchInbox = q.refetch;
+  useEffect(() => { refetchInbox(); }, [state, refetchInbox]);
+
   const items = useMemo<UiInboxItem[]>(() => {
     const inboxItems = q.data ?? [];
     const mailItems: UiInboxItem[] = showMail