fix(agents): instruct orchestrator to output tip in English

Small models (qwen2.5:1.5b) mirror the language of task title content
in the prompt. Adding an explicit English note to snippets that embed
raw task titles (focus-area, overdue-task) prevents language bleed.
Also added the instruction to the orchestrator system prompt and user
message as belt-and-suspenders.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ml/agents/focus_area.py

@@ -88,7 +88,8 @@ class FocusAreaAgent(BaseAgent):
         parts = [
             f'The user\'s most active focus area is "{top.label}" '
             f"({top.task_count} task{'s' if top.task_count != 1 else ''}, "
-            f"{top.overdue_count} overdue)."
+            f"{top.overdue_count} overdue). "
+            f"(Note: task titles may be in any language — always write the tip in English.)"
         ]
         if boosted:
             parts.append("This area matches the user's stated focus preferences.")