fix: improve Amazon auth recovery UX

[eshaffer321]

Summary

• add itemize-native Amazon browser profile cookie import
• support itemize amazon <account> shorthand and reject ambiguous account args
• clean stale Chromium profile singleton markers before import
• replace misleading expired-cookie auth wording with Amazon sign-in rejection wording
• update README and bug-fix log

Tests

• golangci-lint run --timeout=5m
• go test ./...

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.53%. Comparing base (5f6f3c1) to head (197a104).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #63      +/-   ##
==========================================
+ Coverage   60.50%   60.53%   +0.03%     
==========================================
  Files          46       46              
  Lines        5752     5757       +5     
==========================================
+ Hits         3480     3485       +5     
  Misses       2042     2042              
  Partials      230      230              

Flag	Coverage Δ
unittests	60.53% <100.00%> (+0.03%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
internal/adapters/providers/amazon/provider.go	79.06% <100.00%> (+0.62%)	⬆️

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.