Phase 4: Bots & Extensibility

Backend:
- internal/bot/auth.go: bot token generation and verification
- internal/bot/handlers.go: bot CRUD (create, list, get, update, delete, server management, token regen)
- internal/bot/commands.go: slash command registration and management
- internal/webhook/handlers.go: webhook CRUD and execution endpoint
- internal/webhook/token.go: webhook token generation
- internal/db/db.go: bots, bot_servers, slash_commands, webhooks tables
- internal/gateway/events.go: BOT_JOIN, BOT_LEAVE event constants
- cmd/server/main.go: wired bot, webhook, invite routes

Frontend:
- stores/bot.ts: Zustand store for bot management
- BotManager.tsx: bot list, create, edit, delete, add to server, token display
- CommandManager.tsx: slash command CRUD per bot
- SlashCommandPopup.tsx: / command autocomplete popup
- App.tsx: /bots and /bots/:id/commands routes

Examples:
- examples/modbot/: auto-delete banned words, /kick, /ban, /purge commands
- examples/welcome/: welcome message on member join

internal/db/db.go

@@ -137,4 +137,50 @@ CREATE TABLE IF NOT EXISTS invites (
 );
 
 CREATE INDEX IF NOT EXISTS idx_invites_code ON invites(code);
+
+CREATE TABLE IF NOT EXISTS bots (
+	id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+	name VARCHAR(100) NOT NULL,
+	avatar TEXT,
+	description TEXT DEFAULT '',
+	owner_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+	token VARCHAR(64) NOT NULL UNIQUE,
+	created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE TABLE IF NOT EXISTS bot_servers (
+	bot_id UUID NOT NULL REFERENCES bots(id) ON DELETE CASCADE,
+	server_id UUID NOT NULL REFERENCES servers(id) ON DELETE CASCADE,
+	added_by UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+	added_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+	PRIMARY KEY (bot_id, server_id)
+);
+
+CREATE TABLE IF NOT EXISTS slash_commands (
+	id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+	bot_id UUID NOT NULL REFERENCES bots(id) ON DELETE CASCADE,
+	server_id UUID NOT NULL REFERENCES servers(id) ON DELETE CASCADE,
+	name VARCHAR(32) NOT NULL,
+	description TEXT DEFAULT '',
+	options JSONB DEFAULT '[]',
+	created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+	UNIQUE (server_id, name)
+);
+
+CREATE TABLE IF NOT EXISTS webhooks (
+	id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+	channel_id UUID NOT NULL REFERENCES channels(id) ON DELETE CASCADE,
+	name VARCHAR(100) NOT NULL,
+	token VARCHAR(64) NOT NULL,
+	avatar TEXT,
+	created_by UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+	created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_bots_owner ON bots(owner_id);
+CREATE INDEX IF NOT EXISTS idx_bots_token ON bots(token);
+CREATE INDEX IF NOT EXISTS idx_bot_servers_bot ON bot_servers(bot_id);
+CREATE INDEX IF NOT EXISTS idx_slash_commands_server ON slash_commands(server_id, name);
+CREATE INDEX IF NOT EXISTS idx_webhooks_channel ON webhooks(channel_id);
+CREATE INDEX IF NOT EXISTS idx_webhooks_token ON webhooks(token);
 `