fix: restore conditional Go compilation logic to fix module directory errors

- Revert to compiling main.go instead of module directory path
- TinyGo was interpreting directory paths as package imports, not local dirs
- Now compiles main.go directly and TinyGo auto-discovers other .go files
- Fixes calculator_component, http_service_component, simple_test, multi_file_test
- All Go components have main.go so will use file path compilation

Author: avrabe

go/defs.bzl

@@ -232,9 +232,21 @@ def _compile_tinygo_module(ctx, tinygo, go_binary, wasm_opt_binary, wasm_tools,
                 ctx.attr.world,
             ])
 
-    # Always compile the entire Go module directory to include all source files
-    # This ensures TinyGo can see all Go files in the same package, not just main.go
-    tinygo_args.append(go_module_files.path)
+    # Find main Go file path within the module directory
+    main_go_found = False
+    main_go_path = None
+    for src in ctx.files.srcs:
+        if src.basename == "main.go":
+            main_go_path = go_module_files.path + "/main.go"
+            main_go_found = True
+            break
+
+    if main_go_found:
+        tinygo_args.append(main_go_path)
+    else:
+        # If no main.go, compile the entire module directory
+        # This allows TinyGo to see all Go files in the package
+        tinygo_args.append(go_module_files.path)
 
     # Validate that we have Go source files
     go_files = [src for src in ctx.files.srcs if src.extension == "go"]