M6: lightweight markdown rendering on note cards

Render a small Markdown subset in the read view — headings (#..###), bullet/ordered lists, blockquote, fenced code, and inline **bold** / *italic* / `code` — alongside the existing [[wiki-links]] (task 1905). Capture stays plain text; only the card render is formatted.

Hand-rolled dependency-free parser (notes/markdown.ts) rendered as Vue vnodes (MarkdownText/MarkdownInline), never v-html, so there is no HTML-injection surface — matches the no-heavy-dep ethos. Headings require '# ' (space), so a #tag (no space) stays plain text and is never mistaken for a heading; the two coexist. Replaces LinkedText (links-only) on the card; LinkedText deleted.

Pure frontend — no backend/DB/migration.

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

frontend/src/components/MarkdownText.vue

@@ -0,0 +1,36 @@
+<script setup lang="ts">
+import { computed } from "vue";
+import { parseMarkdown } from "../notes/markdown";
+import MarkdownInline from "./MarkdownInline.vue";
+
+const props = defineProps<{ text: string }>();
+const blocks = computed(() => parseMarkdown(props.text));
+</script>
+
+<template>
+  <div class="space-y-1.5 break-words">
+    <template v-for="(b, i) in blocks" :key="i">
+      <h3 v-if="b.type === 'h1'" class="text-base font-bold"><MarkdownInline :tokens="b.inline ?? []" /></h3>
+      <h4 v-else-if="b.type === 'h2'" class="text-sm font-bold"><MarkdownInline :tokens="b.inline ?? []" /></h4>
+      <h5 v-else-if="b.type === 'h3'" class="text-sm font-semibold"><MarkdownInline :tokens="b.inline ?? []" /></h5>
+      <blockquote
+        v-else-if="b.type === 'quote'"
+        class="whitespace-pre-wrap border-l-2 border-neutral-300 pl-2 text-neutral-600 dark:border-neutral-600 dark:text-neutral-400"
+      >
+        <MarkdownInline :tokens="b.inline ?? []" />
+      </blockquote>
+      <ul v-else-if="b.type === 'ul'" class="list-disc space-y-0.5 pl-5">
+        <li v-for="(it, j) in b.items ?? []" :key="j"><MarkdownInline :tokens="it" /></li>
+      </ul>
+      <ol v-else-if="b.type === 'ol'" class="list-decimal space-y-0.5 pl-5">
+        <li v-for="(it, j) in b.items ?? []" :key="j"><MarkdownInline :tokens="it" /></li>
+      </ol>
+      <pre
+        v-else-if="b.type === 'pre'"
+        class="overflow-x-auto whitespace-pre-wrap rounded-md bg-black/5 p-2 font-mono text-xs dark:bg-white/10"
+        >{{ b.value ?? "" }}</pre
+      >
+      <p v-else class="whitespace-pre-wrap"><MarkdownInline :tokens="b.inline ?? []" /></p>
+    </template>
+  </div>
+</template>