Add gRPC and gRPC-Web coverage for missing terminal status

[EffortlessSteven]

What this does

The client suites did not cover the full gRPC and gRPC-Web operation matrix for a valid response message followed by EOF without terminal grpc-status.

Change: add unary, client-streaming, server-streaming, and half-duplex bidi cases for both protocols. Unary and client-streaming must fail without returning a payload; server-streaming and half-duplex bidi must deliver the valid payload before the terminal error. The browser adapter is unchanged; grpc-web's unary and server-streaming behavior is recorded as two narrow known failures.

Verification

Check	Result
reference client	4 operations × 7 server configs, all passed
grpc-go client 1.82.1	4 operations × 1 config, all passed
grpc-web client 1.5.0	2 advertised operations × 1 config: 2 selected, 2 expected failures, 0 unexpected on Node 22
known-failure scope	the 2 patterns match exactly those 2 cases; the divergence reproduces on grpc-web 2.0.2
negative controls	completing the response or omitting the expected payload made representative cases fail
repository gates	make, make checkgenerate, and git diff --check clean in a Linux-native checkout

Review map

• internal/app/connectconformance/testsuites/data/grpc_client_unexpected.yaml: the four native gRPC cases, terminating with no HTTP trailers.
• internal/app/connectconformance/testsuites/data/grpc_web_client_unexpected.yaml: the same operation matrix, omitting the in-body trailers frame.
• testing/grpcwebclient-known-failing.txt: records the official grpc-web divergence for unary and server-streaming, the only operation kinds the client advertises.

Closes #1115.

[jhump]

LGTM. Assuming CI checks out (which I assume it will), the only thing I'd want to tweak is the comment in the known-failing file for grpc-web.