Address review: collapse whitespace in the description footer preview

Embedded newlines rendered as hard breaks in the fixed two-line footer,
clipping later content even under the char budget. Collapse whitespace runs
to single spaces so the footer soft-wraps content across both lines.

Co-authored-by: Isaac <no-reply@databricks.com>

Author: xsh310

src/ucode/ui/interactive_picker.py

@@ -49,6 +49,7 @@ def _description_footer_tokens(description: str) -> list[tuple[str, str]]:
     A caller emphasizes a leading label by formatting the description as ``"label: text"``:
     the ``label:`` renders bold and the rest as the truncated preview. A description with no
     ``": "`` renders entirely as the preview."""
+    description = " ".join(description.split())
     label, sep, body = description.partition(": ")
     if not sep:
         return [("class:instruction", _description_preview(description))]

tests/test_interactive_picker.py

@@ -69,3 +69,8 @@ def test_only_the_body_is_truncated(self):
         label_token, body_token = _description_footer_tokens(f"triage: {long_body}")
         assert label_token == ("bold", "triage: ")
         assert body_token == ("class:instruction", _description_preview(long_body))
+
+    def test_newlines_and_whitespace_runs_collapse_to_single_spaces(self):
+        assert _description_footer_tokens(
+            "Routes tickets.\n\nSeverity from the body.\tEscalates."
+        ) == [("class:instruction", "Routes tickets. Severity from the body. Escalates.")]