Apache Fory: gRPC Code Generation

Apache Fory is a multi-language serialization framework. Its IDL compiler could already emit model types for eleven languages, but gRPC service generation was landing language by language. I owned Dart and Swift: a Fory IDL service definition now produces an idiomatic client and server in both, across all four gRPC shapes and all three schema frontends.

Both PRs are merged into apache/main and shipping. Along the way I found and fixed a runtime divergence in Fory's Swift implementation: under reference tracking, Swift wrote a different reference flag for value-type structs than Java, Rust and C++ did, so Java could not read Swift-produced bytes. Swift now follows the same convention as the other runtimes.

• Dart generator (#3723): client and service base per schema, covering unary, server-streaming, client-streaming and bidirectional RPCs, with no manual Fory registration required at startup.
• Swift generator (#3776): providers, an async client, service metadata and stream adapters for grpc-swift, with a per-thread Fory runtime because the Swift runtime is single-threaded and a shared instance raced under ThreadSanitizer.
• Symbol-collision preflight that fails generation before writing files when two declarations would claim one identifier: namespace enums, duplicates, flattened helpers, names that normalise together, and nested declarations.
• Cross-language interop driven in both directions against a Java peer, across all three schema frontends, wired into CI on every relevant change.
• Reserved-name guarding: generated classes inherit from gRPC base types and Object, so an RPC named `ToString` produced an invalid override. Codegen now detects that and fails with a clear diagnostic.