chore(release): prepare 2.1.0 with Google metadata v9.0.39

[iziz]

Summary

• Update Google libphonenumber metadata from v9.0.38 to v9.0.39 after Upstream Drift run 35175467837.
• Regenerate phone-number, carrier, geocoding, and timezone bundles. The generated testing and short-number metadata are unchanged; the timezone source is unchanged.
• Prepare version 2.1.0 because unreleased changes since 2.0.1 add visionOS support and public Swift 6 concurrency APIs.

Upstream comparison

• Google tag: v9.0.39 (670015c8aec4c3a84769c664f194677201236b43).
• Nine tracked upstream files changed, all metadata or metadata resources. JavaScript implementation, tests, and public API files are unchanged.
• Test parity: 173 upstream JS tests, 181 local Objective-C tests; no missing test names.
• API parity: 66 upstream methods, 93 local Objective-C selectors; no missing public API.
• No tracked source or resource drift from v9.0.39 to Google master at 806ee32e8c8c.

Validation

• Metadata dry run and final freshness check passed.
• Generated and bundled geocoding databases match for all 34 languages.
• Version consistency passed for 2.1.0.
• SwiftPM tests passed in default and Korean locales (231 XCTest plus 43 Swift Testing tests each).
• SwiftPM release build and thread sanitizer suite passed.
• Xcode simulator schemes passed: libPhoneNumber (150), Geocoding (20), ShortNumber (31).
• git diff --check passed.
• All 13 CocoaPods podspecs passed lint; all 11 PR CI jobs passed.