v0.16.1 — Log which custom prompt is actually in effect

A small diagnostic fix. If you're upgrading from 0.15.x, the release worth reading is 0.16.0 — you can now ask the assistant to forget something.

Added

• The server now logs which custom prompt is actually in effect. A client can send customPrompt with a request and it overrides the server-level CUSTOM_PROMPT, but nothing said which one won, and the effective prompt was never logged at any level — so a perfectly good value in one place could sit doing nothing while the other silently took precedence, invisible from outside the process. Two people hit exactly this and reasonably reported it as a personality setting being ignored.

  [persona] … now names the source, previews the first 60 characters, and says explicitly when the server-level prompt is being overridden. Logged once at startup and again only when it changes, so it doesn't repeat per message. If a persona ever seems to be ignored, that line is the first place to look.

Upgrade: no configuration changes required.