feat(electron): main process, vault, search index, links, import, capture

Vault on plain .md files with FTS5 index, link rewriting, canvas files,
history/trash/backup, link previews, image fetch, tasks and unlinked
mentions, Notion/Obsidian importer, quick-capture window and shortcut.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

electron/frontmatter.cjs

@@ -0,0 +1,68 @@
+'use strict';
+// Minimal YAML front matter: flat `key: value`, inline `[a, b]` lists and `- item` lists.
+// Unknown keys are kept and written back, so notes from Obsidian survive a round trip.
+
+const FM = /^?---\r?\n([\s\S]*?)\r?\n---[ \t]*(?:\r?\n|$)/;
+
+function unquote(v) {
+  v = v.trim();
+  if (v.length >= 2 && v.startsWith('"') && v.endsWith('"')) {
+    try { return JSON.parse(v); } catch { return v.slice(1, -1); }
+  }
+  if (v.length >= 2 && v.startsWith("'") && v.endsWith("'")) return v.slice(1, -1).replace(/''/g, "'");
+  return v;
+}
+
+function parseFrontMatter(raw) {
+  const m = raw.match(FM);
+  if (!m) return { meta: {}, body: raw };
+  const meta = {};
+  let last = null;
+  for (const line of m[1].split(/\r?\n/)) {
+    const kv = line.match(/^([A-Za-z0-9_-]+):\s*(.*)$/);
+    if (kv) {
+      last = kv[1];
+      const v = kv[2].trim();
+      if (v.startsWith('[') && v.endsWith(']')) {
+        meta[last] = v.slice(1, -1).split(',').map(unquote).filter(Boolean);
+      } else {
+        meta[last] = v === '' ? [] : unquote(v);
+      }
+      continue;
+    }
+    const item = line.match(/^\s*-\s+(.*)$/);
+    if (item && last) {
+      if (!Array.isArray(meta[last])) meta[last] = [];
+      meta[last].push(unquote(item[1]));
+    }
+  }
+  // An empty `key:` with no list items below it is just an empty string.
+  for (const k of Object.keys(meta)) if (Array.isArray(meta[k]) && !meta[k].length && k !== 'tags') meta[k] = '';
+  return { meta, body: raw.slice(m[0].length).replace(/^\r?\n/, '') };
+}
+
+function quote(s) {
+  s = String(s);
+  return /^[\p{L}\p{N}_ .\/@#+-]+$/u.test(s) && s.trim() === s && !/^[-#@]/.test(s) ? s : JSON.stringify(s);
+}
+
+const ORDER = ['icon', 'cover', 'tags', 'created'];
+
+function serializeFrontMatter(meta = {}) {
+  const keys = Object.keys(meta).filter((k) => {
+    const v = meta[k];
+    return v !== undefined && v !== null && v !== '' && !(Array.isArray(v) && !v.length);
+  });
+  if (!keys.length) return '';
+  keys.sort((a, b) => {
+    const ia = ORDER.indexOf(a), ib = ORDER.indexOf(b);
+    return (ia < 0 ? 99 : ia) - (ib < 0 ? 99 : ib);
+  });
+  const lines = keys.map((k) => {
+    const v = meta[k];
+    return Array.isArray(v) ? `${k}: [${v.map(quote).join(', ')}]` : `${k}: ${quote(v)}`;
+  });
+  return `---\n${lines.join('\n')}\n---\n\n`;
+}
+
+module.exports = { parseFrontMatter, serializeFrontMatter };