Scheduled tasks ignore model setting, always run on Sonnet 4.6

Bug Description

Scheduled tasks always run on Sonnet 4.6 regardless of model configuration. The model setting is not respected through any available mechanism.

Steps to Reproduce

1. Set "model": "claude-opus-4-6" in ~/.claude/settings.json
2. Create a scheduled task via create_scheduled_task API
3. In the Desktop app UI, confirm the task's model is set to Opus 4.6 (via Edit form)
4. Also tried adding model: claude-opus-4-6 to the SKILL.md frontmatter
5. Run the task (either via "Run now" or wait for cron trigger)

Expected Behavior

The task should run using Claude Opus 4.6 as configured.

Actual Behavior

The task always runs on Sonnet 4.6 (visible in the bottom-right corner of the task session window showing "Sonnet 4.6 · High"), regardless of:

• Global settings.json model setting
• UI Edit form model picker selection
• model field in SKILL.md frontmatter (which gets stripped on some tasks)

Environment

• Claude Code Desktop App (macOS)
• Model set to claude-opus-4-6 globally
• Multiple scheduled tasks affected

Impact

Users who need Opus-level reasoning for automated tasks (e.g., code auditing, development, multi-step agentic workflows) cannot configure scheduled tasks to use their preferred model. This is especially impactful for unattended automation where the user cannot intervene.

Additional Context

• The create_scheduled_task and update_scheduled_task APIs do not expose a model parameter
• The SKILL.md frontmatter model field is either stripped or ignored
• The documentation states model can be changed "through the Edit form or ask Claude", but neither method persists the change to actual runtime