build(nix): update npmDepsHash for the MCP SDK dependency

Adding @modelcontextprotocol/sdk changed package-lock.json, so the hash
recorded in nix/package.nix no longer matched and both Nix checks failed on
#893. This is the value the `npmDepsHash matches package-lock.json` job
printed for the lockfile at the PR head.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: 2 people

nix/package.nix

@@ -51,7 +51,7 @@ buildNpmPackage {
       );
     };
 
-  npmDepsHash = "sha256-Rso0fFqexyhMTe3V/gtLWJzRQI8LrUWEPwEdRb2TYTY=";
+  npmDepsHash = "sha256-VeehS9Cp7Z/tcKgPAkjTzRLORqMuSp1pRf2AIOgm6q4=";
 
   env.ELECTRON_SKIP_BINARY_DOWNLOAD = "1";