Squashed commit of the following:

commit 739f9c349031510e8ef010ba2445a2a1fdbec247
Author: Simon Cambier <simon.cambier@protonmail.com>
Date:   Sun Oct 16 16:57:03 2022 +0200

    Code cleaning + README

commit 85762bae592f3eafd34ba22b0cf1841bfbd91ca6
Author: Simon Cambier <simon.cambier@protonmail.com>
Date:   Sun Oct 16 14:59:01 2022 +0200

    Cleaning deleted PDFs from cache

commit 1a37bf38d3f64870d4b40df1b67d8106c893ab64
Author: Simon Cambier <simon.cambier@protonmail.com>
Date:   Sun Oct 16 13:18:06 2022 +0200

    PDF cache saved to IndexedDB

src/database.ts

@@ -0,0 +1,17 @@
+import Dexie from 'dexie'
+
+class OmnisearchCache extends Dexie {
+  pdf!: Dexie.Table<
+    { path: string; hash: string; size: number; text: string },
+    string
+  >
+
+  constructor() {
+    super(app.appId + '_omnisearch')
+    this.version(1).stores({
+      pdf: 'path, hash, size, text',
+    })
+  }
+}
+
+export const database = new OmnisearchCache()