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

cmd/server/main.go

@@ -80,6 +80,11 @@ func main() {
 	hub := gateway.NewHub(database.DB, logger)
 	go hub.Run()
 
+	// Built-in bot runner
+	botRunner := bot.NewRunner(database.DB, hub, logger)
+	botRunner.Register("steamfree", bot.SteamFreeBot)
+	go botRunner.StartAll()
+
 	// Giphy client (nil if no API key)
 	giphyClient := giphy.NewClient(cfg.Giphy.APIKey)
 
@@ -350,7 +355,7 @@ func main() {
 
 			// Bots + slash commands
 			r.Route("/bots", func(r chi.Router) {
-				bot.NewHandler(database.DB).RegisterRoutes(r)
+				bot.NewHandler(database.DB, botRunner).RegisterRoutes(r)
 				bot.NewCommandHandler(database.DB).RegisterCommandRoutes(r)
 			})