Feature: Add robot settings selects (locale, time format, temperature unit, button wakeword)

[MTrab]

Summary

Add HA config entities for core robot settings.

Why this matters (Most-Value)

Persistent robot configuration is a strong fit for HA config entities.

SDK evidence (no wire-pod dependency)

• RPC: UpdateSettings, PullJdocs in external_interface.proto
• Proto: RobotSettingsConfig in settings.proto
• Relevant fields:
  • locale
  • clock_24_hour
  • temp_is_fahrenheit
  • button_wakeword

Proposed HA design

• select.locale
• select.time_format
• select.temperature_unit
• select.button_action
• DISABLED by default

Acceptance criteria

• Current values read from ROBOT_SETTINGS jdoc.
• Writes go through UpdateSettings and validate response code.
• Tests for read + write per entity.