test(html-examples): reconcile keyed search rows

Make the active-search example use a safer keyed reconciliation path for filtered rows: remove filtered-out keys, replace retained keys, and append newly visible keys.

req: list/006

req: htmx_equivalents/001

req: examples/001

REQUIREMENTS.md

@@ -437,6 +437,9 @@ resources. Concrete runtime targets are addressed through `ResourceRef`
 ### req: list/005
 0	005	Compatibility functions such as `append(keyed_slot, key, view)` may exist as explicit low-level forms. Key type mismatches are compile-time errors; missing/ambiguous keys are build errors with template spans. [north_star]
 
+### req: list/006
+0	006	Filtered keyed collections reconcile by removing filtered-out keys, replacing retained keys, and appending newly visible keys rather than clearing and re-adding every row. [north_star]
+
 ---
 
 ## form