Clean up code. Reorganize files. Port stuff from other branches. + more

This turns the project into a monorepo using pnpm workspaces,
dramatically simplifying the build process. It also fixes a lot of bugs
and just generally makes the codebase a lot cleaner.

packages/widget/package.json

@@ -23,6 +23,7 @@
         "lit-element": "^3.1.2"
     },
     "devDependencies": {
+        "@impost/lib": "workspace:*",
         "@types/node": "^20.11.24",
         "lit": "^3.1.2",
         "lit-element": "^3.1.2",
@@ -30,6 +31,7 @@
         "tslib": "^2.6.2",
         "typescript": "^5.3.3",
         "vite": "npm:rolldown-vite@latest",
-        "vite-plugin-dts": "^4.5.4"
+        "vite-plugin-dts": "^4.5.4",
+        "comlink": "^4.4.2"
     }
 }