Fix charmap error on non-ASCII output and add warehouse ID setup step

[vmariiechko]

Summary

Two small improvements to the dbx-ro-query asset triggered by real usage:

1. Encoding fix: query results containing non-ASCII characters (Greek, Cyrillic, emoji) caused a charmap codec error on Windows when printed to stdout. configure_text_streams() reconfigures both stdout and stderr to UTF-8 with errors="replace" at startup. The subprocess call in run_query already used UTF-8; this closes the remaining gap at the print() call in main().

2. Install message: first-time users had no prompt to set DATABRICKS_WAREHOUSE_ID before running the smoke check. A new step 2 in the success_message shows the databricks warehouses list lookup and the export pattern. Placed here rather than in SKILL.md because SKILL.md is read by agents during task execution, not by humans during initial setup.

Changes

• scripts/dbx-ro-query.py: add configure_text_streams(), call it as first line of main()
• databricks_template_schema.json: insert warehouse ID setup step (step 2) in success_message, renumber smoke check to step 3
• tests/assets/test_dbx_ro_query.py: three new tests — configure_text_streams smoke test, non-ASCII scalar output, non-ASCII TSV output
• CHANGELOG.md: add [1.7.1] - 2026-05-13 entry

Change Area

• Asset Library (assets/<name>/)

Configuration Axes Affected

• Asset Library (new asset, asset schema, or framework changes)

Testing

• All tests pass (pytest tests/ -V)
• New tests added for new functionality (if applicable)

Asset Changes (if applicable)

• Asset installs standalone via databricks bundle init . --template-dir assets/<name> --output-dir <dir>
• Asset is self-contained (no references to library/helpers.tmpl or other assets)

Checklist

• Documentation updated (if behavior changed)