Fix CI tests to exclude WASM-specific packages

The runtime and examples packages use syscall/js which only works
with GOOS=js GOARCH=wasm build tags. Exclude these from regular
testing to prevent build constraint failures.

Tested packages:
- cmd/guix (CLI tool)
- internal/cache (incremental compilation)
- pkg/ast (AST definitions)
- pkg/parser (parser with tests)
- pkg/codegen (code generator)

WASM packages (excluded from CI tests):
- pkg/runtime (syscall/js dependent)
- examples/* (WASM applications)

These are validated by the build-wasm job which compiles them
with proper GOOS/GOARCH flags.

Author: claude

.github/workflows/ci.yml

@@ -61,7 +61,14 @@ jobs:
         run: go mod download
 
       - name: Run tests
-        run: go test -v -race -coverprofile=coverage.txt -covermode=atomic ./...
+        run: |
+          # Test non-WASM packages (exclude runtime and examples which use syscall/js)
+          go test -v -race -coverprofile=coverage.txt -covermode=atomic \
+            ./cmd/... \
+            ./internal/... \
+            ./pkg/ast/... \
+            ./pkg/parser/... \
+            ./pkg/codegen/...
 
       - name: Upload coverage
         uses: codecov/codecov-action@v4