v0.6.19

Mobilerun 0.6.19 includes bounded agent finalization, manual OAuth selection and indexed Android tap fixes, refreshed provider defaults and compatibility, and Langfuse support for immutable ended spans.

Provider defaults are GPT-6 Astra with low reasoning, Gemini 3.8 Flash (3.8 Flash Tiered for OAuth), and Claude Sonnet 5. This release pins Android Portal compatibility to 0.7.25.

## What's Changed
* fix(agent): preserve task results during finalization by @lutz-grex in https://github.com/droidrun/mobilerun/pull/442
* fix: honor manual OAuth selection and avoid Android sibling tap obstructions by @RasulOs in https://github.com/droidrun/mobilerun/pull/443
* fix: refresh OAuth defaults and repair provider request compatibility by @RasulOs in https://github.com/droidrun/mobilerun/pull/444
* fix: normalize frozen Langfuse spans and update SDK test usage by @RasulOs in https://github.com/droidrun/mobilerun/pull/445
* chore: release mobilerun 0.6.19 by @RasulOs in https://github.com/droidrun/mobilerun/pull/446


**Full Changelog**: https://github.com/droidrun/mobilerun/compare/v0.6.18...v0.6.19