feat(backend): Implement OAuth2 consent flow with detailed consent management

- Added consent route to handle GET and POST requests for OAuth2 consent.
- Implemented consent details retrieval including user and client information.
- Created schemas for request and response validation using Zod.
- Integrated authorization service to manage authorization requests and codes.
- Added error handling for various scenarios including user authentication and request validation.
- Implemented token route for exchanging authorization codes and refreshing tokens.
- Developed authorization service to validate clients, redirect URIs, and manage authorization requests.
- Introduced cleanup service to periodically remove expired tokens and authorization codes.
- Enhanced token service to generate and verify access and refresh tokens securely.

Author: Lasim

services/backend/api-spec.json

@@ -0,0 +1,41 @@
+CREATE TABLE `oauth_access_tokens` (
+	`id` text PRIMARY KEY NOT NULL,
+	`user_id` text NOT NULL,
+	`client_id` text NOT NULL,
+	`scope` text NOT NULL,
+	`token_hash` text NOT NULL,
+	`created_at` integer NOT NULL,
+	`expires_at` integer NOT NULL,
+	FOREIGN KEY (`user_id`) REFERENCES `authUser`(`id`) ON UPDATE no action ON DELETE cascade
+);
+--> statement-breakpoint
+CREATE UNIQUE INDEX `oauth_access_tokens_token_hash_unique` ON `oauth_access_tokens` (`token_hash`);--> statement-breakpoint
+CREATE TABLE `oauth_authorization_codes` (
+	`id` text PRIMARY KEY NOT NULL,
+	`user_id` text NOT NULL,
+	`client_id` text NOT NULL,
+	`redirect_uri` text NOT NULL,
+	`scope` text NOT NULL,
+	`state` text NOT NULL,
+	`code_challenge` text NOT NULL,
+	`code_challenge_method` text NOT NULL,
+	`code` text NOT NULL,
+	`used` integer DEFAULT false NOT NULL,
+	`created_at` integer NOT NULL,
+	`expires_at` integer NOT NULL,
+	FOREIGN KEY (`user_id`) REFERENCES `authUser`(`id`) ON UPDATE no action ON DELETE cascade
+);
+--> statement-breakpoint
+CREATE UNIQUE INDEX `oauth_authorization_codes_code_unique` ON `oauth_authorization_codes` (`code`);--> statement-breakpoint
+CREATE TABLE `oauth_refresh_tokens` (
+	`id` text PRIMARY KEY NOT NULL,
+	`user_id` text NOT NULL,
+	`client_id` text NOT NULL,
+	`token_hash` text NOT NULL,
+	`used` integer DEFAULT false NOT NULL,
+	`created_at` integer NOT NULL,
+	`expires_at` integer NOT NULL,
+	FOREIGN KEY (`user_id`) REFERENCES `authUser`(`id`) ON UPDATE no action ON DELETE cascade
+);
+--> statement-breakpoint
+CREATE UNIQUE INDEX `oauth_refresh_tokens_token_hash_unique` ON `oauth_refresh_tokens` (`token_hash`);