Embed testbed with tweaks (#9115)

* Nightly source-language update

* add: test embed page for bskyembeds

* run prettier

* wip

* feat: use local dev for bskyembed test.html

* feat: commit generated files which i'm not sure about

* chore: add basic readme to bskyembed

* Revert "feat: commit generated files which i'm not sure about"

This reverts commit b891efdaa1fd7ddd4417bfd5267e861a25a93b0e.

* chore: revert change to bskyembed/.eslintrc.cjs

* chore: remove generated file from bskyweb/static

* chore: revert messages.po changes

* add dev-snippet command, add dev router

* Update README.md

* Update bskyembed/test.html

* change IS_DEV check to allow localhost

---------

Co-authored-by: APiligrim <28320272+APiligrim@users.noreply.github.com>
Co-authored-by: Anastasiya Uraleva <anastasiya@Anastasiyas-MacBook-Pro.local>
Co-authored-by: Anastasiya Uraleva <anastasiya@Mac.localdomain>
Co-authored-by: Elijah Seed-Arita <elijaharita@gmail.com>

bskyembed/package.json

@@ -4,6 +4,7 @@
   "type": "module",
   "scripts": {
     "dev": "vite",
+    "dev-snippet": "tsc --project tsconfig.snippet.json && serve -s dist -p 3000 -n",
     "build": "tsc && vite build",
     "build-snippet": "tsc --project tsconfig.snippet.json",
     "lint": "eslint --cache --ext .js,.jsx,.ts,.tsx src",
@@ -21,6 +22,7 @@
     "eslint-config-preact": "^1.3.0",
     "eslint-plugin-simple-import-sort": "^12.0.0",
     "postcss": "^8.4.38",
+    "serve": "^14.2.5",
     "tailwindcss": "^3.4.3",
     "terser": "^5.43.1",
     "typescript": "^5.8.3",