Inline pastes now flow through more of the message pipeline

What

• The message-ingestion step that processes attachments now reads and passes through a new inline_pastes field on incoming user messages, alongside the existing pasted_content field (used when the host extracts pasted text out of the message instead of leaving it inline).
• The Task tool's input schema now accepts inline_pastes, a list of pasted-text entries that stay in place inside the message content.
• The internal message parser and the peer/bridge message poster now also read and forward inline_pastes, along with a from_plugin field, and messages get tagged with plugin when their origin is known.

Why

This lets pasted text that intentionally stays inline (as opposed to being pulled out into a separate attachment) survive consistently across the input pipeline, the Task tool, and remote/bridge sessions instead of being dropped or only partly supported.