fix(josh-sync): expose yq directly in the consumer devenv module

devenvModules.default only added the wrapProgram-wrapped josh-sync binary,
whose bundled PATH (yq, jq, etc.) only applies while josh-sync itself runs.
Plain `yq` was never actually on PATH in a consumer's devenv shell, breaking
the manual `yq -i` config-editing commands the josh-sync skill's docs call
for. Adds pkgs.yq-go to the module's packages list directly. Bumps to v2.3.1.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TNXgcFWVgSh3wkQS55cCX6

flake.nix

@@ -57,8 +57,15 @@
         });
 
       # devenv module for consumers
+      #
+      # `self.packages.${pkgs.system}.default` is wrapProgram-wrapped, so its
+      # PATH additions (yq, jq, etc.) only apply while `josh-sync` itself is
+      # running — they don't reach the ambient devenv shell. Add yq-go
+      # directly so consumers can run the `yq -i` commands the josh-sync
+      # skill's config-editing docs call for (e.g. schema migrations),
+      # without needing a system-wide yq install.
       devenvModules.default = { pkgs, ... }: {
-        packages = [ self.packages.${pkgs.system}.default ];
+        packages = [ self.packages.${pkgs.system}.default pkgs.yq-go ];
         dotenv.disableHint = true;
       };