feat(filters): surface started/ended date filters on the PlayEvent filter bar

Add Started and Finished DateRangePicker widgets to the PlayEvent filter bar
and wire filter-started / filter-ended into the filter-bar date-range
serializer, so the started/ended DateCriterion fields (added for #67) are
reachable from the UI — enabling "finished in year Y" range filtering.

Builds on #67 (PlayEventFilter.started/ended are DateCriterion); the bare
field names round-trip through _parse_range like the Purchase date fields.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

common/components/filters.py

@@ -1479,6 +1479,8 @@ class PlayEventFilterBar(_FilterBarBase):
 def _playevent_fields(existing: dict) -> list:
     game_choice = _filter_get_choice(existing, "game")
     days_min, days_max = _parse_range(existing, "days_to_finish")
+    started_min, started_max = _parse_range(existing, "started")
+    ended_min, ended_max = _parse_range(existing, "ended")
 
     fields = [
         Div(
@@ -1495,6 +1497,24 @@ def _playevent_fields(existing: dict) -> list:
                 ),
             ],
         ),
+        _filter_field(
+            "Started",
+            DateRangePicker(
+                label="Started",
+                input_name_prefix="filter-started",
+                min_value=started_min,
+                max_value=started_max,
+            ),
+        ),
+        _filter_field(
+            "Finished",
+            DateRangePicker(
+                label="Finished",
+                input_name_prefix="filter-ended",
+                min_value=ended_min,
+                max_value=ended_max,
+            ),
+        ),
         RangeSlider(
             label="Days to Finish",
             input_name_prefix="filter-days-to-finish",