- Peripheral::read/send now return `expected<unique_ptr<Frame>, Error>`
for a unified success/error interface.
- Peripheral::route returns `expected<unique_ptr<Frame>, Error>` to
distinguish intent: (intentional) non-response vs unable to respond
- Other functions with optional message semantics (handle,poll,react)
return a unique_ptr whose ownership-state indicates response intent
(i.e. send new message)
Bundled necessary changes:
- Switch Frame allocation from global to local (enabled via member
function new/delete)
- Add new header-library tl::expected to shim avr-libstdcpp
Unrelated: Defensive `continue` added after `route`, to reduce Bus
activity check latency
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Allen Hill