Add /nebula framer rewrite in dashboard (#5414)

## Problem solved

Short description of the bug fixed or feature added

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## PR-Codex overview
This PR updates the routing paths in the `apps/dashboard/framer-rewrites.js` file by adding a new route and modifying existing ones.

### Detailed summary
- Added the route `"/nebula"`.
- Changed the `"/connect/sign-in"` route to `"/connect/sign-in"` (no change).
- Modified the `"/contracts/modular-contracts"` route.
- Modified the `"/contracts/explore"` route.

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Author: MananTank

apps/dashboard/framer-rewrites.js

@@ -5,6 +5,7 @@ module.exports = [
   // -- product landing pages --
   // -- connect
   "/connect/sign-in",
+  "/nebula",
   // -- contracts
   "/contracts/modular-contracts",
   "/contracts/explore",