review: an undo concludes again only what it had deleted

Undoing a consolidate concluded its moved entries a second time, and a later
removal deleted only the newer conclusion. An undo's added entry is now
concluded only when the ledger decided a Conclude for it and then an
Unconclude: an entry still concluded, or never concluded (a secret session's,
one from before sync), gets nothing. Ledger::concluded and unconcluded answer
from the decisions, in a module of their own to keep ledger.rs under 500 lines.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/memoryd/src/honcho/mod.rs

@@ -1,6 +1,7 @@
 //! Honcho, the memory this agent shares with the fleet, reached through `roncho` (M5c spec).
 
 pub mod client;
+pub mod concluded;
 pub mod config;
 pub mod decide;
 pub mod edits;