- MediaStore: use full UUID to prevent ref collisions, preserve and
expose metadata via ResolveWithMeta, include underlying OS errors
- Agent loop: populate MediaPart Type/Filename/ContentType from
MediaStore metadata so channels can dispatch media correctly
- SplitMessage: fix byte-vs-rune index mixup in code block header
parsing, remove dead candidateStr variable
- Pico auth: restrict query-param token behind AllowTokenQuery config
flag (default false) to prevent token leakage via logs/referer
- HandleMessage: replace context.TODO with caller-propagated ctx,
log PublishInbound failures instead of silently discarding
- Gateway shutdown: use fresh 15s timeout context for StopAll so
graceful shutdown is not short-circuited by the cancelled parent ctx
Message splitting is exclusively a Manager responsibility. Moving it
into the channels package eliminates the cross-package dependency and
aligns with the refactoring plan.