feat: implement workout session API client functions

[Lance-Yuriel]

📝 Description

This PR implements the client-side HTTP requests for workout session API functions in src/shared/lib/workout-session/workout-session.api.ts. The functions were previously returning empty arrays or placeholder values instead of making actual requests to the server.

Key Changes:

• getAll() - Implemented GET requests to /api/workout-sessions to fetch all workout sessions
• create() - Implemented POST requests to /api/workout-sessions to create new workout sessions
• update() - Implemented PATCH requests to /api/workout-sessions/:id to update existing sessions
• complete() - Implemented PATCH requests to /api/workout-sessions/:id/complete to mark sessions as completed

Integration & Architecture:

• Integrated all API functions into useWorkoutSessionService with proper fallbacks to server actions
• Added direct API calls to workout-session.store.ts for workout completion flow
• Maintained backward compatibility with existing server action patterns
• Added comprehensive error handling with graceful fallbacks

Testing & Verification:

• All 4 API functions tested and working with real network calls
• Verified proper HTTP requests in browser dev tools (GET, POST, PATCH)
• Confirmed error handling and fallback mechanisms work correctly
• Tested complete workout flow end-to-end

📋 Checklist

• My code follows the project conventions
• This PR includes breaking changes
• I have updated documentation if necessary

🗃️ Prisma Migrations (if applicable)

• I have created a migration
• I have tested the migration locally

📸 Screenshots (if applicable)

Network Tab Evidence:

• Console logs show successful API calls: 🔄 Attempting to complete workout via API and ✅ Workout completed via API
• Network tab shows proper HTTP requests initiated by workout-session.api.ts
• Terminal logs confirm server responses: PATCH /api/workout-sessions/1759890128120/complete 200 in 1680ms

🔗 Related Issues

Resolves: Client-side API implementation for workout sessions

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