feat(x): add typed X API v2 client, cached metrics with freshness TTL…

[Mikey-222]

SUMMARY

• Add XApiClient with getUserByHandle and getUserById (X API v2)
• Add fetchAndRefreshXMetrics with 30-min freshness TTL
• Update refreshXMetrics to iterate linked handles via Promise.allSettled
• Add x.types.ts, x.schema.ts, x.controller.ts, x.routes.ts
• Add x.fixtures.ts for test data
• Add notifications module with list/get/markRead/markAllRead endpoints
• Add full OpenAPI path definitions for all new endpoints
• Wire up routers in app.ts
• All tests mocked (no real network calls)

Description

Closes #

Type of Change

Please mark the options that are relevant:

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 🧪 Tests (adding new tests or updating existing tests)
• 📝 Documentation (changes to documentation/configs only)
• 🚀 DevOps & CI/CD (changes to workflows, scripts, or templates)

Changes Made

• C

How to Test

Checklist

💻 Smart Contract Changes (if applicable)

• Running cargo fmt -- --check passes successfully.
• Running cargo clippy -- -D warnings runs without any warnings.
• All tests pass successfully using cargo test.
• New unit or integration tests have been written to cover the changes.
• No hardcoded values are present (e.g. addresses, fees) that should be configurable.

🎨 Frontend Changes (if applicable)

• TypeScript compiles cleanly with no errors (npm run typecheck or npx tsc --noEmit).
• Running npm run lint shows no linting errors.
• The production build compiles successfully via npm run build.
• Changes verified on local browser environment with Freighter/xBull/Albedo wallet.
• Responsive design verified (tested on mobile, tablet, and desktop viewport sizes).
• Keyboard navigation and accessibility (a11y) considerations are addressed.

⚙️ General

• Code follows the project's coding standards and structure guidelines.

• Self-reviewed the changes to ensure clean code with no commented-out code blocks.

• No console.log or debug code remains in production files.

• The branch is up-to-date with the main branch.

• closes X: X metrics endpoint GET /x/:handle/metrics #976

• closes Notifications: Notifications API docs #969

• closes X: X API client wrapper #970

• closes X: Cache X metrics (XAccount + Redis) #972

[drips-wave]

@Mikey-222 Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits