Remove Claude model override workaround

[Manho]

Summary

• remove the experimental Panelize Claude model selector, warning banner, and request interceptor
• preserve the standard Claude integration and clean up the retired claudeModelMode setting during extension updates
• remove obsolete localization, privacy, and test coverage while adding regression checks for the native-selection path

Verification

• npx vitest run --exclude="tests/e2e/**" (297 tests passed)
• npm run release:package
• verified that Claude currently exposes its native model selector and Extended control

The existing release preparation and publishing workflows are unchanged.