feat(backend): implement OAuthDiscoveryService for detecting and discovering OAuth metadata from MCP servers

Author: Lasim

services/backend/drizzle/migrations_sqlite/0014_low_penance.sql

@@ -0,0 +1,19 @@
+CREATE TABLE `mcpOauthTokens` (
+	`id` text PRIMARY KEY NOT NULL,
+	`installation_id` text NOT NULL,
+	`user_id` text NOT NULL,
+	`team_id` text NOT NULL,
+	`access_token` text NOT NULL,
+	`refresh_token` text,
+	`token_type` text DEFAULT 'Bearer' NOT NULL,
+	`expires_at` integer,
+	`scope` text,
+	`created_at` integer NOT NULL,
+	`updated_at` integer NOT NULL,
+	FOREIGN KEY (`installation_id`) REFERENCES `mcpServerInstallations`(`id`) ON UPDATE no action ON DELETE cascade,
+	FOREIGN KEY (`user_id`) REFERENCES `authUser`(`id`) ON UPDATE no action ON DELETE cascade,
+	FOREIGN KEY (`team_id`) REFERENCES `teams`(`id`) ON UPDATE no action ON DELETE cascade
+);
+--> statement-breakpoint
+CREATE INDEX `mcp_oauth_tokens_installation_user_team_idx` ON `mcpOauthTokens` (`installation_id`,`user_id`,`team_id`);--> statement-breakpoint
+ALTER TABLE `mcpServers` ADD `requires_oauth` integer DEFAULT false NOT NULL;