Use TYPE_URL instead of TYPE_CONTENT for path alias language resolution

Problem

DomainSourcePathProcessor::processOutbound() uses LanguageInterface::TYPE_CONTENT to determine the langcode for entity translation lookup. It should use TYPE_URL instead, so that the entity translation matches the language conveyed by the URL.

Core's AliasManager::getAliasByPath() explicitly defaults to TYPE_URL with this rationale:

If no language is explicitly specified we default to the current URL language. If we used a language different from the one conveyed by the requested URL, we might end up being unable to check if there is a path alias matching the URL path.

When the content language and URL language diverge (which can happen depending on language negotiation settings), using TYPE_CONTENT can produce incorrect cross-domain rewrites.

Proposed fix

• Change TYPE_CONTENT to TYPE_URL for the langcode fallback
• Change the cache context from languages:language_content to languages:language_url