feat: add GetWithAssistedSupport for Company endpoint 202 handling

[travisjoseph]

Summary

• Adds GetWithAssistedSupport() method to handle 202 responses from assisted connections
• Implements union response type (Company | CompanyDataSyncInProgress)
• Follows existing PayStatement pattern for union discrimination
• Non-generated file won't be overwritten by codegen

Problem

For assisted connections, /employer/company endpoint returns 202 status when data sync is in progress. Current SDK only expects Company struct, causing deserialization failures.

Solution

Created company_assisted.go with union response types:

• Company variant for 200 OK with data
• CompanyDataSyncInProgress variant for 202 sync status
• Type-safe pattern matching via AsUnion() method

Usage

resp, err := client.HRIS.Company.GetWithAssistedSupport(ctx)
switch u := resp.AsUnion().(type) {
case finchgo.Company:
    // Process company data
case finchgo.CompanyDataSyncInProgress:
    // Retry later - data syncing
}

Test Plan

• ✅ Unit tests for 200 response (deserializes to Company)
• ✅ Unit tests for 202 response (deserializes to CompanyDataSyncInProgress)
• ✅ Example program demonstrating usage pattern
• ✅ All existing tests still pass (verified internal package tests)

🤖 Generated with Claude Code