fix(runtime): revert Bun 1.4.0 -> 1.3.14 to fix Telegram sendDocument socket-close

Bun 1.4.0 (upgraded 0deb607) breaks Telegraf 4.15 sendDocument with
'The socket connection was closed unexpectedly' — reproduced with the same
libraries: Telegraf 4.15.0 on Bun 1.4.0 fails exactly like prod, on Bun 1.3.14
it returns a proper HTTP response. All uploads 500 since the upgrade deployed
(Aug 29 11:06). Pin flake nix override + CI bun-version to 1.3.14.

.github/workflows/deploy.yml

@@ -29,7 +29,7 @@ jobs:
 
       - uses: oven-sh/setup-bun@v2
         with:
-          bun-version: "1.4.0"
+          bun-version: "1.3.14"
 
       - name: Install deps
         run: bun install --frozen-lockfile