build(nix): add shellHook for MCP mock server dependencies

- Add automatic pnpm install for vendor/stackone-ai-node in shellHook
- Update submodule to latest commit
- Fix pnpm version reference (pnpm -> pnpm_10)

Author: ryoppippi

flake.nix

@@ -101,19 +101,28 @@
 
               # Node.js for MCP mock server
               bun
-              pnpm
+              pnpm_10
               typescript-go
             ];
 
             shellHook = ''
               echo "StackOne AI Python SDK development environment"
 
-              # Install dependencies only if .venv is missing or uv.lock is newer
+              # Install Python dependencies only if .venv is missing or uv.lock is newer
               if [ ! -d .venv ] || [ uv.lock -nt .venv ]; then
-                echo "📦 Installing dependencies..."
+                echo "📦 Installing Python dependencies..."
                 uv sync --all-extras
               fi
 
+              # Install Node.js dependencies for MCP mock server (used in tests)
+              if [ -d vendor/stackone-ai-node ]; then
+                if [ ! -f vendor/stackone-ai-node/node_modules/.pnpm/lock.yaml ] || \
+                   [ vendor/stackone-ai-node/pnpm-lock.yaml -nt vendor/stackone-ai-node/node_modules/.pnpm/lock.yaml ]; then
+                  echo "📦 Installing MCP mock server dependencies..."
+                  (cd vendor/stackone-ai-node && pnpm install --frozen-lockfile)
+                fi
+              fi
+
               # Install git hooks
               ${config.pre-commit.installationScript}
             '';