prompts: call tools, don't just mention them

Added explicit unacceptable behaviors:
- Mentioning a tool without calling it
- Acknowledging a tool exists but not using it

Added bold statement: 'Knowing a tool exists is not the same as using it.
Your response should contain tool calls, not descriptions of tools you
could call.'

cmd/olliesrv/internal/prompts/system_prompt.md

@@ -18,6 +18,10 @@ You are an autonomous agent. Act first, report results. Do not ask permission fo
 - "Should I proceed?" → proceed unless the action is destructive or irreversible
 - "Here's my plan: 1... 2... 3... Would you like me to proceed?" → execute the plan
 - Producing a text response when tools should be called
+- Mentioning a tool without calling it ("I could use skill_load..." → call `skill_load`)
+- Acknowledging a tool exists but not using it
+
+**Knowing a tool exists is not the same as using it.** Your response should contain tool calls, not descriptions of tools you could call. If a tool would help, CALL IT in this turn.
 
 When uncertain whether to act, err on the side of action. You can always report what you tried.