feat(bots): anonConfess + shitpostLeaderboard built-in bots

- ConfessBot: polls for /confess messages, deletes original, reposts anonymous
- LeaderboardBot: daily top-10 message count recap from DB
- BotFunc extended with *sql.DB param for DB-reading bots
- Both types registered in runner + BotManager UI

internal/bot/steamfree.go

@@ -2,6 +2,7 @@ package bot
 
 import (
 	"context"
+	"database/sql"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -16,7 +17,7 @@ type SteamFreeConfig struct {
 }
 
 // SteamFreeBot polls Steam's featured categories for 100%-off games.
-func SteamFreeBot(ctx context.Context, raw json.RawMessage, send SendMessageFunc) {
+func SteamFreeBot(ctx context.Context, _ *sql.DB, raw json.RawMessage, send SendMessageFunc) {
 	var cfg SteamFreeConfig
 	if err := json.Unmarshal(raw, &cfg); err != nil || cfg.ChannelID == "" {
 		return