build(channel): consolidate feature flags and documentation #216

Parent: #206

Resolution

The 0.7 feature and documentation structure is finalized:

• Keep oneshot, mpsc, broadcast, and watch as independent opt-in Cargo features matching the public delivery families that are implemented.
• Do not add a channel umbrella feature. It would not provide a stable audit, dependency, or compilation boundary beyond enabling unrelated APIs together.
• Do not create feature flags for producer topology or bounded versus unbounded policy. Those choices remain visible in module paths and constructors, such as broadcast::mpmc::unbounded and mpsc::bounded.
• Keep public modules and source families at direct crate-root paths. Shared implementation machinery remains private under crate::internal when it is genuinely shared.
• Document each feature and public module in the README and crate-level API map.

Completed by

• docs(channel): clarify feature boundaries #226 established the feature decision and documented the feature boundaries.
• refactor(channel): simplify channel structure #234 aligned the physical source tree with the public module families without changing feature names or public import paths.
• docs: refine 0.7 release documentation #235 is a release-documentation follow-up that makes the shipped channel topology more explicit; it does not change the decision above.

Future aggregate or topology-specific features require a concrete compile-time, dependency, binary-size, or audit boundary and can be proposed independently.