Add gRPC server-side streaming response support

[ryanfowler]

Switch gRPC response handling from buffered single-frame processing to an incremental frame reader that reads and formats each message as it arrives. This uses the same streaming pattern as SSE and NDJSON formatters, and works for both unary (single frame) and server-streaming (multiple frames) responses.

Also adds gRPC trailer status reporting: non-OK grpc-status trailers are now printed to stderr with the appropriate error message, and the exit code is set to 1.

[Copilot]

Pull request overview

This PR adds support for gRPC server-side streaming responses by switching from buffered single-frame processing to an incremental frame reader. The implementation reads and formats each message as it arrives, following the same streaming pattern as SSE and NDJSON formatters. Additionally, it introduces gRPC trailer status reporting to print non-OK grpc-status trailers to stderr and set the exit code to 1.

Changes:

• Introduced ReadFrame function for incremental gRPC frame reading from io.Reader
• Implemented FormatGRPCStream to handle both unary and server-streaming responses
• Added gRPC trailer status checking and error reporting

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
internal/grpc/framing.go	Added ReadFrame function to incrementally read gRPC frames and moved maxMessageSize constant to package level
internal/grpc/framing_test.go	Added comprehensive tests for ReadFrame covering single frames, multiple frames, edge cases, and round-trip validation
internal/format/grpc.go	New file implementing FormatGRPCStream for streaming gRPC response formatting
internal/format/grpc_test.go	New test file with coverage for various streaming scenarios including single/multiple frames and error handling
internal/fetch/proto.go	Added checkGRPCStatus function to parse and report gRPC trailer status codes
internal/fetch/fetch.go	Refactored to use streaming approach for gRPC responses and check trailer status after body consumption
internal/fetch/clipboard.go	Updated to exclude gRPC from clipboard copying alongside other streaming response types
integration/integration_test.go	Added integration tests for gRPC streaming responses and error status handling
docs/grpc.md	Updated documentation to describe server streaming support, gRPC status reporting, and revised limitations

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