feat: add MyFitnessPal integration and external provider settings UI

[serjsv87]

• Add MyFitnessPalService for MFP data sync via Garmin integration
• Add mfpRoutes (/api/integrations/myfitnesspal/sync, /status)
• Add mfpSyncService for syncing daily food totals
• Extend externalProviderRepository with MFP-aware queries
• Add ExternalProviderSettings UI with ProviderCard, AddExternalProviderForm, EditProviderForm, ProviderSpecificFields components
• Add useIntegrations hook and externalProviderService API client
• Add myfitnesspal provider type to settings

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Description

What problem does this PR solve?
Adds MyFitnessPal integration for syncing food diary data via Garmin, and introduces a redesigned External Provider Settings UI that makes managing all third-party integrations consistent and user-friendly.

How did you implement the solution?
Added myFitnessPalService.ts (MFP API client), mfpSyncService.ts (daily totals sync), and mfpRoutes.ts (POST /api/integrations/myfitnesspal/sync, GET /status). Extended externalProviderRepository.ts with MFP-aware queries. On the frontend, refactored provider settings into reusable components: ExternalProviderSettings, ProviderCard, AddExternalProviderForm, EditProviderForm, and ProviderSpecificFields. Added useIntegrations hook and externalProviderService API client.

Linked Issue: #

How to Test

1. Check out this branch and run pnpm run validate
2. Start the server
3. Navigate to Settings → External Providers
4. Add a MyFitnessPal provider with your credentials
5. Trigger a sync via POST /api/integrations/myfitnesspal/sync
6. Verify food entries appear in the food log for the synced dates

PR Type

• Issue (bug fix)
• New Feature
• Refactor
• Documentation

Checklist

All PRs:

• [MANDATORY - ALL] Integrity & License: I certify this is my own work, free of malicious code, and I agree to the License terms.

New features only:

• [MANDATORY for new feature] Alignment: I have raised a GitHub issue and it was reviewed/approved by maintainers or it was approved on Discord.

Frontend changes (SparkyFitnessFrontend/ or src/):

• [MANDATORY for Frontend changes] Quality: I have run pnpm run validate and it passes.
• [MANDATORY for Frontend changes] Translations: I have only updated the English (en) translation file.

Backend changes (SparkyFitnessServer/):

• [MANDATORY for Backend changes] Code Quality: I have run typecheck, lint, and tests. New files use TypeScript, new endpoints have Zod schemas, and new endpoints include tests.
• [MANDATORY for Backend changes] Database Security: I have updated rls_policies.sql for any new user-specific tables. (Note: No new tables added; uses existing external_data_providers table).

UI changes (components, screens, pages):

• [MANDATORY for UI changes] Screenshots: I have attached Before/After screenshots below.

Screenshots

Click to expand

Before

(add screenshot of old provider settings)

After

(add screenshot of new ExternalProviderSettings UI)

Notes for Reviewers

Optional — use this for anything that doesn't fit above: known tradeoffs, areas you'd like specific feedback on, qustions you have or context that helps reviewers.

[gemini-code-assist]

Code Review

This pull request introduces a comprehensive integration with MyFitnessPal (MFP), enabling users to sync their nutrition data from SparkyFitness to their MFP diary. The changes span the entire stack, including frontend UI for credential management (CSRF tokens and session cookies), manual sync triggers, and status monitoring. The backend implementation features a new MFP service that handles complex authentication flows, data mapping, and an idempotent sync process that clears existing entries before pushing new totals. Additionally, the PR adds Ukrainian language support and refactors some provider settings. Review feedback highlights opportunities to improve type safety by replacing any with specific interfaces or unknown, optimizing sequential network requests during the deletion phase of the sync, and addressing potential scalability issues with the in-memory sync lock.