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/seed.cjs

@@ -0,0 +1,50 @@
+'use strict';
+// First-run content for an empty notes folder.
+const fsp = require('node:fs').promises;
+const path = require('node:path');
+const { today } = require('./vault.cjs');
+
+const GETTING_STARTED = `Everything here is plain Markdown in this folder. No account, no sync, nothing leaves this computer.
+
+A quiet place to write. Pages nest like folders, tags live in each file's front matter, and search runs against a local index.
+
+## Write the way you think
+
+- Type \`/\` on any line to add a heading, to-do, quote, toggle or code block.
+- Start a line with \`#\`, \`-\`, \`[]\`, \`>\` or three backticks and it turns into that block as you type.
+- Hover a block and drag the handle on its left to move it.
+- Press <kbd>Ctrl</kbd> <kbd>K</kbd> to search every note or run a command.
+
+## First steps
+
+- [x] Pick a folder for your notes
+- [ ] Write one page, however short
+- [ ] Try the light theme from the switch in the sidebar
+
+<details>
+<summary>Where do my files actually live?</summary>
+
+Each page is a \`.md\` file in this folder. A page with sub-pages gets a folder of the same name. The search index sits in \`.notes/index.sqlite\`; delete it any time and it rebuilds on launch.
+
+</details>
+
+> Notes are for thinking, not for filing.
+`;
+
+async function isEmpty(dir) {
+  try {
+    const entries = await fsp.readdir(dir);
+    return entries.filter((n) => !n.startsWith('.')).length === 0;
+  } catch (err) {
+    if (err.code === 'ENOENT') return true;
+    throw err;
+  }
+}
+
+async function seedVault(dir) {
+  await fsp.mkdir(dir, { recursive: true });
+  const fm = `---\nicon: sparkle\ncover: blush\ntags: [guide]\ncreated: ${today()}\n---\n\n`;
+  await fsp.writeFile(path.join(dir, 'Getting started.md'), fm + GETTING_STARTED, 'utf8');
+}
+
+module.exports = { isEmpty, seedVault, GETTING_STARTED };