feat(plugin-honcho): show what Honcho remembers about you

The opt-in page gains a debug panel, once the user's saved flag is on:
service status (reachability, latency, the caller's own processing
queue, with the specific Honcho error when something is wrong), a full
overview (peer card, derived facts with ids, summary) and one text
field with two actions — search (raw ranked facts) and ask (Honcho's
server-side LLM answers), plus an in-page mini-guide.

Every endpoint gates on the per-user opt-in server-side, fail closed,
and derives the peer from the authenticated Caller — never from the
request body — since the workspace is shared. Honcho 404s are
translated per-endpoint as 'no memory yet' rather than failures.

CHANGELOG.md

@@ -10,6 +10,13 @@ release PR may merge — and a section is closed at the commit that bumps it.
 
 ### Added
 
+- The **Long-term memory** page (Honcho plugin) now shows, once you have opted in, what
+  Honcho actually remembers about you: a service-status line (connected/unreachable with
+  the specific error, and your memory's processing queue), a full overview (your card,
+  derived facts, summary) and a search-or-ask box — *search* returns the raw stored facts
+  matching your words, *ask* has Honcho's AI answer a question in its own words. A
+  built-in mini-guide explains the difference. Errors say what went wrong (unreachable
+  host, rejected key, server error), not just "unavailable".
 - The assistant can now explain the **file viewer**, the **Tasks page**, your **Profile**
   and the admin's **Users** page: ask it what a document's history button does, why a
   `.tex` is shown instead of a PDF, how to stop a recurring job without losing it, what a