Recompile components after modify_file to prevent test pollution

The integration test rendered CacheableComponent inside a modify_file
block, which compiles a render_template_for method with the modified
template source directly onto the component class. Restoring the file
via modify_file's ensure did not undo that method redefinition, so
subsequent tests that rendered CacheableComponent kept seeing the
temporarily-modified output ('changed').

Invalidating the CompileCache after modify_file restores the file forces
the next render to recompile from the restored source, isolating the
modification to the block that requested it.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: joelhawksley

test/test_helper.rb

@@ -165,6 +165,12 @@ def modify_file(file, content)
     yield
   ensure
     File.open(filename, "wb+") { |f| f.write(old_content) }
+    # A component that rendered while `file` was modified had its
+    # `render_template_for` method defined against the modified source. That
+    # method stays on the class until the compiler runs again, so invalidate
+    # every compiled component's cache entry: the next render of any of them
+    # recompiles from the now-restored file.
+    ViewComponent::CompileCache.invalidate!
   end
 end