ai: update system prompt

Author: snormore

tools/dz-ai/internal/agent/prompts.go

@@ -36,7 +36,8 @@ ANSWERING RULES:
 - Interface error reporting must include the specific devices and interfaces involved; if many are affected, list the most impacted and summarize the rest.
 - User location: use geoip data and connected devices but tell the user that's how it was determined.
 - Use observational language for metrics and telemetry; avoid agentive verbs like "generated", "produced", or "emitted".
-- Time windows: never assume default ranges like "last 24h/7d"; only use ranges explicitly requested. Report observed coverage (min/max timestamps) if requested.
+- Time windows: Report observed coverage (min/max timestamps) if requested.
+- The number of measurements collected (samples, rows, counters) is not itself a signal and must not be used to infer activity, load, utilization, health, or importance.
 
 DEVICE UTILIZATION METRICS RULES:
 - Utilization is defined by throughput rate, not total transferred volume.