feat: add envelopes (#2025)

This PR is handles the changes required to support envelopes. The new
envelope editor/signing page will be hidden during release.

The core changes here is to migrate the documents and templates model to
a centralized envelopes model.

Even though Documents and Templates are removed, from the user
perspective they will still exist as we remap envelopes to documents and
templates.

packages/lib/package.json

@@ -43,7 +43,6 @@
     "micro": "^10.0.1",
     "nanoid": "^5.1.5",
     "oslo": "^0.17.0",
-    "pdf-lib": "^1.17.1",
     "pg": "^8.11.3",
     "pino": "^9.7.0",
     "pino-pretty": "^13.0.0",
@@ -53,6 +52,7 @@
     "react": "^18",
     "remeda": "^2.17.3",
     "sharp": "0.32.6",
+    "skia-canvas": "^3.0.8",
     "stripe": "^12.7.0",
     "ts-pattern": "^5.0.5",
     "zod": "3.24.1"