Use TIMMY_STATUS_PROMPT in CLI status command

TIMMY_STATUS_PROMPT was defined in timmy/prompts.py and covered by
tests, but never wired into the application. The CLI status command
was passing a hardcoded inline string instead. Replace the inline
string with the canonical prompt and add two CLI tests that verify
the correct prompt is used.

https://claude.ai/code/session_01DMjQ5qMZ8iHeyix1j3GS7c

src/timmy/cli.py

@@ -1,6 +1,7 @@
 import typer
 
 from timmy.agent import create_timmy
+from timmy.prompts import TIMMY_STATUS_PROMPT
 
 app = typer.Typer(help="Timmy — sovereign AI agent")
 
@@ -23,7 +24,7 @@ def chat(message: str = typer.Argument(..., help="Message to send")):
 def status():
     """Print Timmy's operational status."""
     timmy = create_timmy()
-    timmy.print_response("Brief status report — one sentence.", stream=False)
+    timmy.print_response(TIMMY_STATUS_PROMPT, stream=False)
 
 
 def main():