website: file transfer page (#6644)

* add implementation plan

* website: remove unnecessary libsodium direct dependency from file page plan

* website: update file page plan for async encryption, tailwind, no worker

* add product plan

* update product plan based on the feedback

* remove implementation details from product plan

* update product plan

* add updated implementation plan

* website: add build infrastructure for /file route

* website: fix card click and overlay hash handling for /file page

* website: add /file page with XFTP file transfer and protocol overlay

* website: redesign /file page layout and styling

* fix(website): scope hero h1/h2 font overrides to .hero-section-1

* fix(website): fix /file overlay diagram scaling on short viewports

* style(website): match /file page top padding with /directory

* website: remove file page in navbar

* website: switch xftp-web to official one

* website: fix web.sh

* update texts

---------

Co-authored-by: Evgeny Poberezkin <evgeny@poberezkin.com>

website/src/_data/file_overlays.json

@@ -0,0 +1,16 @@
+{
+    "sections": [
+        {
+            "id": 1,
+            "imgLight": "/img/new/xftp-protocol.svg",
+            "imgDark": "/img/new/xftp-protocol-dark.svg",
+            "overlayContent": {
+                "overlayId": "xftp-protocol",
+                "overlayScrollTo": "",
+                "title": "file-protocol-title",
+                "showImage": true,
+                "contentBody": "overlay_content/file/protocol.html"
+            }
+        }
+    ]
+}