M3 reminders: notes.remind_at + Reminders view

- Migration 0010: notes.remind_at (nullable tz). PATCH accepts remind_at
  (ISO set / null clear); GET /api/notes/reminders (soonest first, non-trashed);
  serialize includes remind_at.
- Frontend: datetime util (local<->ISO, format, overdue); notes store setReminder;
  editor datetime-local picker + clear; card reminder chip (overdue = red);
  sidebar Reminders entry + /reminders view.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FRgehjoz7Yv8LkUfADxACm

frontend/src/views/RemindersView.vue

@@ -0,0 +1,57 @@
+<script setup lang="ts">
+import { onMounted, ref } from "vue";
+import { api } from "../api/client";
+import { useNotesStore, type Note } from "../stores/notes";
+import NoteCard from "../components/NoteCard.vue";
+import NoteEditor from "../components/NoteEditor.vue";
+
+const notes = useNotesStore();
+const items = ref<Note[]>([]);
+const loading = ref(true);
+const editing = ref<Note | null>(null);
+
+async function load() {
+  loading.value = true;
+  try {
+    const res = await api.get<{ notes: Note[] }>("/api/notes/reminders");
+    items.value = res.notes;
+  } finally {
+    loading.value = false;
+  }
+}
+
+function openEditor(n: Note) {
+  editing.value = n;
+}
+async function closeEditor() {
+  editing.value = null;
+  await load();
+}
+async function onNavigate(id: string) {
+  const found = items.value.find((n) => n.id === id) ?? notes.items.find((n) => n.id === id);
+  editing.value = found ?? (await notes.fetchOne(id));
+}
+
+onMounted(load);
+</script>
+
+<template>
+  <div class="mx-auto w-full max-w-6xl px-4 py-6">
+    <h1 class="mb-4 text-lg font-semibold">Reminders</h1>
+
+    <div v-if="loading" class="py-24 text-center text-sm text-neutral-400">Loading…</div>
+
+    <div v-else-if="items.length === 0" class="py-24 text-center">
+      <h2 class="text-lg font-semibold text-neutral-700 dark:text-neutral-200">No reminders</h2>
+      <p class="mt-1 text-sm text-neutral-400">Set a reminder on a note (in its editor) to see it here.</p>
+    </div>
+
+    <div v-else class="columns-1 gap-4 sm:columns-2 lg:columns-3 xl:columns-4">
+      <NoteCard v-for="n in items" :key="n.id" :note="n" @open="openEditor" />
+    </div>
+
+    <template v-if="editing">
+      <NoteEditor :note="editing" @close="closeEditor" @navigate="onNavigate" />
+    </template>
+  </div>
+</template>