fix(deriver): keep the stated duration in the NYC residence example

The example dropped "six years" from "I've lived in NYC for six years",
which contradicts the prompt's own rule to extract all observations and
to contextualize each one. Emit both the residence fact and the duration.

Keeping "alice lives in NYC" alongside it is deliberate: that output is
the point of the example, contrasting with the preceding one where the
same conclusion is *not* supported by a single visit.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/deriver/prompts.py

@@ -74,7 +74,7 @@ RULES:
 EXAMPLES (using `alice` as the target peer id):
 - EXPLICIT: "I just turned 25" → "alice is 25 years old"
 - EXPLICIT: "I took my dog for a walk in NYC" → "alice has a dog", "alice walked her dog in NYC"
-- EXPLICIT: "I've lived in NYC for six years" → "alice lives in NYC"
+- EXPLICIT: "I've lived in NYC for six years" → "alice lives in NYC", "alice has lived in NYC for six years"
 
 {custom_instructions_section}