fix(sess): keep sess version locked to extension version

The previous commit bumped sess to 3.0.1 to force needs_install on
reattach, but a test asserts sess DESCRIPTION version equals the base
extension version in package.json (currently 3.0.0-rc.0 -> 3.0.0). The
standalone bump broke that invariant on all three test runners.

Revert sess to 3.0.0. The reconnect fix still ships with this branch's
release; version lockstep with the extension is left to the maintainers'
release process rather than bumped independently here.

Author: grantmcdermott

sess/DESCRIPTION

@@ -1,7 +1,7 @@
 Package: sess
 Type: Package
 Title: Modern R IPC Server
-Version: 3.0.1
+Version: 3.0.0
 Author: Gemini
 Maintainer: Gemini <gemini@example.com>
 Description: Implements a high-performance IPC client for R sessions using Unix domain sockets and Windows named pipes. Replaces legacy file-system watcher based workflows while keeping JSON-RPC communication semantics for IDE/editor integration.