Add DM support, friend identification, and target pruning

React in 1:1 DMs alongside servers/groups, surface the resolved friend
username at startup and in the stats panel, verify reactions actually
stick after adding them (with jump links for manual spot-checking),
and prune stale targets from stats on each run so only the currently
mutual set is shown.

bot/reactor.py

@@ -26,6 +26,7 @@ async def react_to_message(
     emoji: str,
     source: str,
     display: Optional[StatsDisplay] = None,
+    verify: bool = True,
 ) -> bool:
     if message.author.id != friend_id:
         return False
@@ -46,6 +47,20 @@ async def react_to_message(
         log.exception("Failed to react to message %s in channel %s", message.id, message.channel.id)
         return False
 
+    if verify:
+        try:
+            refetched = await message.channel.fetch_message(message.id)
+            confirmed = any(r.me and str(r.emoji) == emoji for r in refetched.reactions)
+        except discord.HTTPException:
+            confirmed = None  # couldn't verify either way; don't block on it
+
+        if confirmed is False:
+            log.warning(
+                "Reaction API call succeeded but is NOT visible on refetch! "
+                "message=%s channel=%s target=%s (%s) url=%s",
+                message.id, message.channel.id, target.name, target.target_type, message.jump_url,
+            )
+
     inserted = await asyncio.to_thread(
         storage.record_reaction,
         message.id,
@@ -57,7 +72,10 @@ async def react_to_message(
         message.created_at,
     )
     if inserted:
-        log.info("Reacted to message %s in %s [%s] (%s)", message.id, target.name, target.target_type, source)
+        log.info(
+            "Reacted to message in %s [%s] (%s): %s",
+            target.name, target.target_type, source, message.jump_url,
+        )
         if display is not None:
             await display.refresh()
     return inserted