[CI logging] Add CI logger activation and distributed logging

### Summary

Add opt-in CI logger activation, GitHub Actions environment detection, and distributed logger registration.

### Background and Motivation

The MVP must be safe to evaluate without changing existing output by default. It must also work correctly when MSBuild uses worker nodes.

### Proposed Feature

Add explicit `on`, `off`, and `auto` configuration for the CI logger. In `auto` mode, select the GitHub Actions writer only when the GitHub Actions environment is detected.

Register the CI logger as a distributed logger and forward only the events needed for annotations. Preserve existing Console Logger, Binary Logger, response-file, and `/noconlog` semantics.

Configuration precedence and final switch/environment-variable names will be defined as part of this work.

Validation should cover explicit activation and opt-out, environment detection, configuration precedence, `/m`, worker-node diagnostics, duplicate prevention, and coexistence with existing loggers.

### Alternative Designs

Automatic default activation is outside the MVP because additional output can break log parsers. A later default-on experience will require a compatibility assessment, explicit opt-out, and likely a ChangeWave.

No files, tests, or entry points are named; start by locating the existing logger activation, GitHub Actions detection, distributed-logger, worker-node, and response-file handling paths. Define the configuration names and precedence, then validate explicit opt-in and opt-out, auto detection, /m diagnostics, duplicate prevention, and coexistence with existing loggers.

Written by the indexing model from the issue text.