Add comprehensive API v1 with OAuth and API key authentication (#2389)

* OAuth

* Add API test routes and update Doorkeeper token handling for test environment

- Introduced API namespace with test routes for controller testing in the test environment.
- Updated Doorkeeper configuration to allow fallback to plain tokens in the test environment for easier testing.
- Modified schema to change resource_owner_id type from bigint to string.

* Implement API key authentication and enhance access control

- Replaced Doorkeeper OAuth authentication with a custom method supporting both OAuth and API keys in the BaseController.
- Added methods for API key authentication, including validation and logging.
- Introduced scope-based authorization for API keys in the TestController.
- Updated routes to include API key management endpoints.
- Enhanced logging for API access to include authentication method details.
- Added tests for API key functionality, including validation, scope checks, and access control enforcement.

* Add API key rate limiting and usage tracking

- Implemented rate limiting for API key authentication in BaseController.
- Added methods to check rate limits, render appropriate responses, and include rate limit headers in responses.
- Updated routes to include a new usage resource for tracking API usage.
- Enhanced tests to verify rate limit functionality, including exceeding limits and per-key tracking.
- Cleaned up Redis data in tests to ensure isolation between test cases.

* Add Jbuilder for JSON rendering and refactor AccountsController

- Added Jbuilder gem for improved JSON response handling.
- Refactored index action in AccountsController to utilize Jbuilder for rendering JSON.
- Removed manual serialization of accounts and streamlined response structure.
- Implemented a before_action in BaseController to enforce JSON format for all API requests.

* Add transactions resource to API routes

- Added routes for transactions, allowing index, show, create, update, and destroy actions.
- This enhancement supports comprehensive transaction management within the API.

* Enhance API authentication and onboarding handling

- Updated BaseController to skip onboarding requirements for API endpoints and added manual token verification for OAuth authentication.
- Improved error handling and logging for invalid access tokens.
- Introduced a method to set up the current context for API requests, ensuring compatibility with session-like behavior.
- Excluded API paths from onboarding redirects in the Onboardable concern.
- Updated database schema to change resource_owner_id type from bigint to string for OAuth access grants.

* Fix rubocop offenses

- Fix indentation and spacing issues
- Convert single quotes to double quotes
- Add spaces inside array brackets
- Fix comment alignment
- Add missing trailing newlines
- Correct else/end alignment

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Fix API test failures and improve test reliability

- Fix ApiRateLimiterTest by removing mock users method and using fixtures
- Fix UsageControllerTest by removing mock users method and using fixtures
- Fix BaseControllerTest by using different users for multiple API keys
- Use unique display_key values with SecureRandom to avoid conflicts
- Fix double render issue in UsageController by returning after authorize_scope\!
- Specify controller name in routes for usage resource
- Remove trailing whitespace and empty lines per Rubocop

All tests now pass and linting is clean.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Add API transactions controller warning to brakeman ignore

The account_id parameter in the API transactions controller is properly
validated on line 79: family.accounts.find(transaction_params[:account_id])
This ensures users can only create transactions in accounts belonging to
their family, making this a false positive.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Signed-off-by: Josh Pigford <josh@joshpigford.com>
Co-authored-by: Claude <noreply@anthropic.com>

test/integration/oauth_basic_test.rb

@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class OauthBasicTest < ActionDispatch::IntegrationTest
+  test "oauth authorization endpoint requires authentication" do
+    oauth_app = Doorkeeper::Application.create!(
+      name: "Test API Client",
+      redirect_uri: "https://client.example.com/callback",
+      scopes: "read"
+    )
+
+    get "/oauth/authorize?client_id=#{oauth_app.uid}&redirect_uri=#{CGI.escape(oauth_app.redirect_uri)}&response_type=code&scope=read"
+
+    # Should redirect to login page when not authenticated
+    assert_redirected_to new_session_path
+  end
+
+  test "oauth token endpoint exists and handles requests" do
+    post "/oauth/token", params: {
+      grant_type: "authorization_code",
+      code: "invalid_code",
+      redirect_uri: "https://example.com/callback",
+      client_id: "invalid_client"
+    }
+
+    # Should return 401 for invalid client (correct OAuth behavior)
+    assert_response :unauthorized
+    response_body = JSON.parse(response.body)
+    assert_equal "invalid_client", response_body["error"]
+  end
+
+  test "oauth applications can be created" do
+    assert_difference("Doorkeeper::Application.count") do
+      Doorkeeper::Application.create!(
+        name: "Test App",
+        redirect_uri: "https://example.com/callback",
+        scopes: "read"
+      )
+    end
+  end
+
+  test "doorkeeper configuration is properly set up" do
+    # Test that Doorkeeper is configured and working
+    assert Doorkeeper.configuration.present?, "Doorkeeper configuration should exist"
+    assert_equal 1.year, Doorkeeper.configuration.access_token_expires_in
+    assert_equal "read", Doorkeeper.configuration.default_scopes.first.to_s
+  end
+end