* [Examples][Tests] Make the MCP Apps example work over HTTP, and pin it
It was the only example without a session store, so every request under
`php -S` or php-fpm - each its own process - was answered "Session not found
or has expired". It now uses a FileSessionStore like the others.
Inspector snapshots pin what the extension actually puts on the wire: the
ui:// resource's `text/html;profile=mcp-app` MIME type and `ui` marker, and
the `_meta.ui` on the tool that links the two.
* Apply suggestion from @chr-hertel
* Apply suggestion from @chr-hertel
