Port gRPC logger and severity gating

Scope

Port Bun corpus position 3983, js/third_party/grpc-js/test-logging.test.ts.

Required contracts

• expose @grpc/grpc-js/build/src/logging
• support logger replacement and retrieval
• gate DEBUG, INFO, and ERROR records by configured verbosity
• expose public grpc.setLogger, grpc.setLogVerbosity, and grpc.logVerbosity
• preserve custom logger failures as causes with logging-operation/severity/source stack context

Verification

• focused upstream file passes without unsupported cases
• permanent diagnostics cover gating and a throwing custom logger
• existing gRPC, SQL adapter, and third-party gates remain green

Implemented and pushed in 9810ff913.

Completed contracts:

• exposed @grpc/grpc-js/build/src/logging
• implemented shared logger replacement/retrieval state
• implemented DEBUG, INFO, ERROR, and NONE verbosity gating
• exposed grpc.setLogger, grpc.setLogVerbosity, and grpc.logVerbosity
• partial loggers safely ignore unavailable output methods
• throwing custom loggers produce ERR_GRPC_LOGGER with the original cause and logging-operation, severity, and source-module stack context

Verification:

• focused Bun corpus: 2 passed, 0 failed, 0 todo, 0 unsupported
• permanent gRPC diagnostics: 10 passed
• SQL adapter contracts: passed
• permanent third-party JWT/utility mini-suite: passed
• zig fmt --check and git diff --check: passed

Cumulative through position 3983: 325 files, 2,664 passed, 209 todo, 0 failed, 0 unsupported, 171 allowed-empty.