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>

config/initializers/rack_attack.rb

@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+class Rack::Attack
+  # Enable Rack::Attack
+  enabled = Rails.env.production? || Rails.env.staging?
+
+  # Throttle requests to the OAuth token endpoint
+  throttle("oauth/token", limit: 10, period: 1.minute) do |request|
+    request.ip if request.path == "/oauth/token"
+  end
+
+  # Throttle API requests per access token
+  throttle("api/requests", limit: 100, period: 1.hour) do |request|
+    if request.path.start_with?("/api/")
+      # Extract access token from Authorization header
+      auth_header = request.get_header("HTTP_AUTHORIZATION")
+      if auth_header&.start_with?("Bearer ")
+        token = auth_header.split(" ").last
+        "api_token:#{Digest::SHA256.hexdigest(token)}"
+      else
+        # Fall back to IP-based limiting for unauthenticated requests
+        "api_ip:#{request.ip}"
+      end
+    end
+  end
+
+  # More permissive throttling for API requests by IP (for development/testing)
+  throttle("api/ip", limit: 200, period: 1.hour) do |request|
+    request.ip if request.path.start_with?("/api/")
+  end
+
+  # Block requests that appear to be malicious
+  blocklist("block malicious requests") do |request|
+    # Block requests with suspicious user agents
+    suspicious_user_agents = [
+      /sqlmap/i,
+      /nmap/i,
+      /nikto/i,
+      /masscan/i
+    ]
+
+    user_agent = request.user_agent
+    suspicious_user_agents.any? { |pattern| user_agent =~ pattern } if user_agent
+  end
+
+  # Configure response for throttled requests
+  self.throttled_responder = lambda do |request|
+    [
+      429, # status
+      {
+        "Content-Type" => "application/json",
+        "Retry-After" => "60"
+      },
+      [ { error: "Rate limit exceeded. Try again later." }.to_json ]
+    ]
+  end
+
+  # Configure response for blocked requests
+  self.blocklisted_responder = lambda do |request|
+    [
+      403, # status
+      { "Content-Type" => "application/json" },
+      [ { error: "Request blocked." }.to_json ]
+    ]
+  end
+end