Modify LGU+ IMS user agent to Google device carrier settings

[imnyang]

Summary

• Add ims.ims_user_agent_string to the LG U+ carrier settings for 20 Google Pixel devices.
• Set the IMS user-agent string to:
  TTA-VoLTE/3.0 #MODEL#/#BUILD# Device-Type/Android_Phone OMD
• Regenerate the corresponding .pb files and update the associated vendor spec SHA-256 hashes.

Rationale

The LG U+ carrier settings previously did not define an IMS user-agent string. This change adds the carrier-specific value while preserving the per-device #MODEL# and #BUILD# placeholders.

Validation

• Confirmed at an LG U+ retail store that the Google Pixel 6 Pro can be registered as "Domestic unreleased foreign device (OMD-STDPHONE)", the operator profile used for devices not officially released in South Korea.
• Tested the change on an actual Google Pixel 6 Pro with an LG U+ USIM card (not eSIM).
• Confirmed that device activation completed successfully by receiving the LG U+ activation confirmation SMS.
• Verified that IMS registration completed successfully and that VoLTE calls work correctly.
• Verified that the SHA-256 hashes of all 20 generated lguplus_kr.pb files match their corresponding vendor spec entries.

Note

English is not my native language, so this description was translated with the assistance of an LLM. There may be minor differences in wording from the original Korean text.