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/confess.go

@@ -0,0 +1,79 @@
+package bot
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"fmt"
+	"strings"
+	"time"
+)
+
+// ConfessConfig: "channel_id" is where anonymous confessions land.
+type ConfessConfig struct {
+	ChannelID string `json:"channel_id"`
+}
+
+// ConfessBot watches for /confess messages, deletes the original, reposts anonymously.
+func ConfessBot(ctx context.Context, db *sql.DB, raw json.RawMessage, send SendMessageFunc) {
+	var cfg ConfessConfig
+	if err := json.Unmarshal(raw, &cfg); err != nil || cfg.ChannelID == "" {
+		return
+	}
+
+	lastID := ""
+	ticker := time.NewTicker(10 * time.Second)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			confessPoll(db, cfg.ChannelID, &lastID, send)
+		}
+	}
+}
+
+func confessPoll(db *sql.DB, targetChannel string, lastID *string, send SendMessageFunc) {
+	q := `SELECT id, channel_id, content FROM messages
+		WHERE content ILIKE '/confess%' AND bot_id IS NULL
+		ORDER BY created_at ASC LIMIT 10`
+	if *lastID != "" {
+		q = `SELECT id, channel_id, content FROM messages
+			WHERE content ILIKE '/confess%' AND bot_id IS NULL AND created_at::text > (SELECT created_at::text FROM messages WHERE id = $1)
+			ORDER BY created_at ASC LIMIT 10`
+	}
+
+	var rows *sql.Rows
+	var err error
+	if *lastID != "" {
+		rows, err = db.QueryContext(context.Background(), q, *lastID)
+	} else {
+		rows, err = db.QueryContext(context.Background(), q)
+	}
+	if err != nil {
+		return
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		var id, channelID, content string
+		if err := rows.Scan(&id, &channelID, &content); err != nil {
+			continue
+		}
+		*lastID = id
+
+		// Strip "/confess" prefix
+		text := strings.TrimSpace(strings.TrimPrefix(content, "/confess"))
+		if text == "" {
+			continue
+		}
+
+		// Delete the original message
+		db.ExecContext(context.Background(), `DELETE FROM messages WHERE id = $1`, id)
+
+		// Repost anonymously
+		send(targetChannel, fmt.Sprintf("🕵️ **anonymous confession:** %s", text))
+	}
+}