Add UNO addbot, fix audit issues, add fishing to superstats, update README

UNO addbot:
- !uno addbot / !uno removebot for lobby bot management (WinBee, GwinBee)
- Bots ante from community pot, increasing the total pot
- Single human can start a game if bots fill remaining slots
- Per-bot display names throughout (replaces global unoBotName)

Audit fixes:
- Lobby display now always shows both humans and bots (was omitting bots on join)
- Slot check accounts for bots (was only counting humans)
- Color Roulette bot victim name fixed (was showing acting bot's name)
- Lobby display built under lock to prevent stale reads
- Bot name list separated from env var to prevent duplicates
- Extracted shared buildLobbyDisplay helper
- Inlined unnecessary nameOf closure in sudden death

Other:
- T5 masterwork drop rate reduced from 1.5% to 0.5%
- Added fishing stats to !superstatsexplusalpha
- Updated README with all new features

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/plugin/uno_nomercy.go

@@ -201,10 +201,7 @@ func (p *UnoPlugin) checkMultiMercyElimination(game *unoMultiGame, player *unoMu
 	}
 
 	player.active = false
-	name := p.DisplayName(player.userID)
-	if player.isBot {
-		name = unoBotName()
-	}
+	name := p.multiName(player)
 
 	// Shuffle cards back into draw pile
 	game.drawPile = append(game.drawPile, player.hand...)
@@ -226,7 +223,7 @@ func (p *UnoPlugin) checkMultiMercyElimination(game *unoMultiGame, player *unoMu
 		if len(active) == 1 {
 			winner := active[0]
 			if winner.isBot {
-				p.multiBotWins(game)
+				p.multiBotWins(game, winner)
 			} else {
 				p.multiPlayerWins(game, winner)
 			}