* [Capability] Remove CompletionProvider's dead providerClass argument
It always threw on construction, so it never worked in any release. `provider:`
takes the same class-string and is now the first positional argument.
* Reword Changelog
* harden sampling tools against the spec
Report tool-flow violations as -32602 instead of dropping the request,
accept resource_link in tool results, gate tools on sampling.tools, and
reject empty content.
* normalize keyed content arrays to lists
array_filter() and friends preserve keys, and a keyed array serializes as a
JSON object instead of the content-block array the schema requires.
* [Client] Implement setMaxRetries connection retries
* [Client] Reject a negative retry count in Configuration
* [Client] Use a positive init timeout in the retry test
* [Client] Drop redundant docblock note on setMaxRetries
* [Client] Clear the initialized flag on a failed connection
* [Client] Trim comments to the non-obvious ones
* [Client] Cover retries and timeout cleanup with integration tests
The retry fixture counts the processes it was started as, which is what
separates a real retry from a second call into the same server. The timeout
fixture outlives the client's patience and then goes idle, so the next
request runs on a connection the client already gave up on once.
* [Tests] Introduce client-server integration tests
* Add an in-process loopback that connects a real client transport to a real
server transport, draining both Fiber loops in one synchronous pass instead
of polling. A stalled exchange fails where it happened rather than hanging.
* Cover protocol version negotiation across both implementations, where the
unit tests only ever drive one side against a canned counter-offer.
* Cover the server-to-client round-trips end to end: elicitation, sampling,
roots, plus progress and logging notifications.
* Add the `integration` test suite and a `make integration-tests` target.
* [Tests] Run the integration suite in CI
The unit job pins `--testsuite=unit`, so the new suite would never have run on
GitHub. It goes in that job rather than its own: the loopback leans on Fibers,
and the matrix is what covers them down to the PHP 8.1 floor.
* [Tests] Run integration tests against a real server process
Replaces the in-process loopback with the setup from examples/client: the
client spawns a fixture server over the real StdioTransport, so the tests
exercise the shipped transports and no longer nest both sides' Fibers.
Moves the suite into its own CI job, matrixed over PHP 8.1-8.5.
