Support debugging raw API data

[ZeroTricks]

Support saving all raw API data belonging to a conversation (requests, responses) to a file. File can be (ND)JSON.
Can be called via (names TBD)

• log.rawApiDataToFile: true, for all
• /dumpToFile, requested manually

Advantages:

• no dependence on conversation sync
• easier to debug client integrations
• no need to rely on conversations.sync.includeSystemMessages for troubleshooting non-user messages and tool/function calls
• option could still respect log.messageContent

Questions:

• is this useful for CLI?
• what exactly should be dumped? (API Turns → in-memory Conversations → Turns to Lumo)