Same rule applied to production code in earlier commits now applies to
tests: Http::fake patterns and assertions read from
config('trypost.platforms.*.oauth_api' / '.api' / '.default_service')
instead of hardcoded strings. Hardcoded URLs in tests drift silently
when the config changes.
Also documents the rule in CLAUDE.md under "External Service URLs" so
new code (and tests) start in the right place — only the host comes
from config, path/RPC segments stay inline next to the call.
LinkedInPageAnalytics and MastodonAnalytics were the only two of the 11
files refactored to read OAuth host / default instance from config that
had zero test coverage. Adds smoke tests that assert the HTTP request
hits the configured URL, so a typo in the config key (e.g. linkedin.api
vs linkedin.oauth_api) would now fail loudly.
