Update DASHBOARD_BUILDER skill for AWS + reduced prompts

- Use MCP tools (app_get_url) instead of wb app list for app UUID
- Mark packages as pre-installed, skip pip install unless import fails
- Fix Flask route decorators (leading slash required)
- Clarify JS fetch relative path rule vs Flask route rule
- Add Aurora IAM auth template and MCP-first query approach
- Add S3 data dashboard template
- Keep BigQuery template for GCP workspaces
- Remove emoji from headers for cleaner output

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: PeterSu92