Add settings page for managing forecasting API key and URL via UI

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/node_modules/recharts/AGENTS.md

@@ -0,0 +1,26 @@
+This is Recharts repository. Recharts is a React-based charting library.
+The goal is to provide a simple, declarative, and composable way to build charts.
+We value consistency, usability, and performance. Accessibility is important.
+
+We do not solve internationalization. Do not hardcode any strings or formatting choices in the library code,
+we expect the users of Recharts to provide localized strings as desired.
+
+Read ./DEVELOPING.md for instructions how to develop this project.
+
+Read ./CONTRIBUTING.md for guidelines on contributing to this project.
+
+When running unit tests, prefer to run a single test file:
+
+```shell
+npm run test -- path/to/TestFile.spec.tsx
+```
+
+If you run all tests at once using `npm test`, it may take a long time to complete.
+Only do that when you want to verify that everything is working correctly.
+
+This project has a long history. You may observe some inconsistencies in coding style.
+When making changes, prefer current best practices as described in CONTRIBUTING.md,
+and try to improve the code style where possible and where relevant to the current task.
+Do not attempt to fix too much at once, or when it is not related to the current changes.
+
+Do not focus too much on fitting the existing style, if it is not ideal.