feat(bots): built-in bot runner + steamfree from UI

- BotRunner: server-side goroutine manager for built-in bot types
- steamfree bot embedded in server (polls Steam API, posts free games)
- bot_type + config JSONB columns on bots table
- Create/Update/Delete handlers manage runner lifecycle
- GET /bots/types returns registered bot types
- BotManager: type selector dropdown + config fields on create
- No SSH needed: create a 'Steam Free Games' bot from /bots/manage

internal/bot/runner.go

@@ -0,0 +1,197 @@
+package bot
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"log/slog"
+	"sync"
+
+	"git.dustin.coffee/hobokenchicken/dumpsterChat/internal/gateway"
+)
+
+// BotFunc is the signature for a built-in bot type's run function.
+// It blocks until ctx is cancelled. Use send to post messages.
+type BotFunc func(ctx context.Context, config json.RawMessage, send SendMessageFunc)
+
+// SendMessageFunc posts a message to a channel as this bot.
+type SendMessageFunc func(channelID, content string)
+
+// Runner manages server-side bot goroutines.
+type Runner struct {
+	db     *sql.DB
+	hub    *gateway.Hub
+	logger *slog.Logger
+
+	mu      sync.Mutex
+	bots    map[string]context.CancelFunc // botID -> cancel
+	types   map[string]BotFunc            // type name -> runner
+}
+
+func NewRunner(db *sql.DB, hub *gateway.Hub, logger *slog.Logger) *Runner {
+	return &Runner{
+		db:    db,
+		hub:   hub,
+		logger: logger,
+		bots:  make(map[string]context.CancelFunc),
+		types: make(map[string]BotFunc),
+	}
+}
+
+// Register adds a built-in bot type.
+func (r *Runner) Register(name string, fn BotFunc) {
+	r.types[name] = fn
+}
+
+// StartAll loads all bots with a bot_type set and starts them.
+func (r *Runner) StartAll() {
+	rows, err := r.db.QueryContext(context.Background(),
+		`SELECT id, bot_type, config::text FROM bots WHERE bot_type != ''`)
+	if err != nil {
+		r.logger.Error("failed to load bot configs", "error", err)
+		return
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		var id, botType, configStr string
+		if err := rows.Scan(&id, &botType, &configStr); err != nil {
+			continue
+		}
+		r.Start(id, botType, json.RawMessage(configStr))
+	}
+}
+
+// Start starts a single bot by ID. Safe to call multiple times (restarts).
+func (r *Runner) Start(botID, botType string, config json.RawMessage) {
+	r.mu.Lock()
+	// Stop existing if running
+	if cancel, ok := r.bots[botID]; ok {
+		cancel()
+		delete(r.bots, botID)
+	}
+
+	fn, ok := r.types[botType]
+	if !ok {
+		r.mu.Unlock()
+		r.logger.Warn("unknown bot type", "type", botType, "bot_id", botID)
+		return
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	r.bots[botID] = cancel
+	r.mu.Unlock()
+
+	send := r.makeSender(botID)
+	r.logger.Info("starting built-in bot", "bot_id", botID, "type", botType)
+
+	go func() {
+		defer func() {
+			if rec := recover(); rec != nil {
+				r.logger.Error("bot panic", "bot_id", botID, "type", botType, "panic", rec)
+			}
+		}()
+		fn(ctx, config, send)
+		r.logger.Info("bot stopped", "bot_id", botID, "type", botType)
+	}()
+}
+
+// Stop stops a single bot by ID.
+func (r *Runner) Stop(botID string) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if cancel, ok := r.bots[botID]; ok {
+		cancel()
+		delete(r.bots, botID)
+	}
+}
+
+// IsRunning checks if a bot is currently running.
+func (r *Runner) IsRunning(botID string) bool {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	_, ok := r.bots[botID]
+	return ok
+}
+
+// makeSender returns a SendMessageFunc that inserts into DB and broadcasts.
+func (r *Runner) makeSender(botID string) SendMessageFunc {
+	return func(channelID, content string) {
+		if len(content) > 4000 {
+			content = content[:4000]
+		}
+
+		// Look up bot info + server
+		var botName, ownerID string
+		err := r.db.QueryRowContext(context.Background(),
+			`SELECT name, owner_id FROM bots WHERE id = $1`, botID,
+		).Scan(&botName, &ownerID)
+		if err != nil {
+			r.logger.Error("send: bot not found", "bot_id", botID, "error", err)
+			return
+		}
+
+		serverID, err := r.hub.ServerIDForChannel(context.Background(), channelID)
+		if err != nil {
+			r.logger.Error("send: channel not found", "channel_id", channelID, "error", err)
+			return
+		}
+
+		// Verify bot is in this server
+		var inServer bool
+		err = r.db.QueryRowContext(context.Background(),
+			`SELECT EXISTS(SELECT 1 FROM bot_servers WHERE bot_id = $1 AND server_id = $2)`,
+			botID, serverID,
+		).Scan(&inServer)
+		if err != nil || !inServer {
+			r.logger.Warn("send: bot not in server", "bot_id", botID, "server_id", serverID)
+			return
+		}
+
+		var msgID, createdAt string
+		err = r.db.QueryRowContext(context.Background(),
+			`INSERT INTO messages (channel_id, author_id, content, bot_id)
+			 VALUES ($1, $2, $3, $4)
+			 RETURNING id, created_at::text`,
+			channelID, ownerID, content, botID,
+		).Scan(&msgID, &createdAt)
+		if err != nil {
+			r.logger.Error("send: insert failed", "error", err)
+			return
+		}
+
+		r.hub.BroadcastToServer(serverID, gateway.Event{
+			Type: gateway.EventMessageCreate,
+			Data: map[string]interface{}{
+				"id":                  msgID,
+				"channel_id":          channelID,
+				"author_id":           ownerID,
+				"author_username":     botName,
+				"author_display_name": nil,
+				"author_bot":          true,
+				"bot_id":              botID,
+				"bot_name":            botName,
+				"content":             content,
+				"reply_to":            nil,
+				"edited_at":           nil,
+				"pinned":              false,
+				"created_at":          createdAt,
+				"embeds":              []interface{}{},
+				"reactions":           []interface{}{},
+			},
+		})
+	}
+}
+
+// RegisteredTypes returns the list of available bot type names.
+func (r *Runner) RegisteredTypes() []string {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	names := make([]string, 0, len(r.types))
+	for k := range r.types {
+		names = append(names, k)
+	}
+	return names
+}
+
+