fix: complete rename from fetch to pup in remaining code references

[jkirsteins]

Summary

Complete the project rename from "fetch" to "pup" started in commit 2901608.

Changes

• internal/version/version.go:17 - Change "Fetch" to "Pup" in BuildInfo()
• pkg/auth/storage/factory.go:122 - Fix path in warning message
• cmd/auth.go:34 - Fix help text

Testing

• Built and ran pup version - shows "Pup" correctly
• All existing tests pass
• No functional changes, only display text

Related

This cleanup enables PR #2 for user agent enhancement to stay focused.

[github-actions]

📊 Test Coverage Report

Overall Coverage: 80.1%

Threshold: 80% ✅

Coverage by Package

## Coverage by Package

- github.com/DataDog/pup/pkg/auth/callback/server.go:40: 81.2%
- github.com/DataDog/pup/pkg/auth/dcr/client.go:28: 100.0%
- github.com/DataDog/pup/pkg/auth/dcr/types.go:24: 100.0%
- github.com/DataDog/pup/pkg/auth/oauth/client.go:22: 100.0%
- github.com/DataDog/pup/pkg/auth/oauth/pkce.go:24: 85.7%
- github.com/DataDog/pup/pkg/auth/storage/factory.go:53: 94.7%
- github.com/DataDog/pup/pkg/auth/storage/keychain.go:44: 42.9%
- github.com/DataDog/pup/pkg/auth/storage/storage.go:58: 71.4%
- github.com/DataDog/pup/pkg/auth/types/types.go:23: 100.0%
- github.com/DataDog/pup/pkg/client/client.go:33: 94.4%
- github.com/DataDog/pup/pkg/config/config.go:22: 100.0%
- github.com/DataDog/pup/pkg/formatter/formatter.go:31: 100.0%
- github.com/DataDog/pup/pkg/util/time.go:20: 95.8%

## Summary

total:								(statements)		80.1%

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📈 Coverage Status: ✅ PASSED - Coverage meets minimum threshold

_{Updated for commit 956b617}