docs(va): two-parameter report shot with a date literal

Replaces the three-parameter screenshot with a two-parameter one - a value
list and a date - and adds a zoomed crop of the DC header and FILTER line.

The date parameter arrives as a display date and is rendered as a SAS date
literal ('12FEB1960'd), the same as a date filter built inside Data
Controller. That is worth showing because VA's own prompt containers in the
report header show only the parameter label: the FILTER line is where the
selected values are legible.

docs/visual-analytics.md

@@ -50,9 +50,9 @@ VA pushes a JSON payload to the iframe via `window.postMessage` whenever the sel
 
 If VA sends an empty / unmatched message the editor falls back to the unfiltered view but stays in VA mode.
 
-The applied filter is shown above the grid, so what the report did to the editor is visible without touching it.  In the report below, three report parameters - `SOME_CHAR`, `SOME_DROPDOWN` and `SOME_NUM` - reach one Data Controller object, and the editor shows both the combined filter and the single row it matches:
+The applied filter is shown above the grid, so what the report did to the editor is visible without touching it.  In the report below, two report parameters - `SOME_DROPDOWN` and `SOME_DATE` - reach one Data Controller object, and the editor shows both the combined filter and the single row it matches:
 
-![Three report parameters driving the embedded editor](img/va-report-filters.png)
+![A value and a date parameter filtering the embedded editor](img/va-report-filters.png)
 
 More logic available in [`va-messaging.service.ts`](https://git.datacontroller.io/dc/dc/src/branch/main/client/src/app/services/va-messaging.service.ts).
 
@@ -184,6 +184,10 @@ The mapping lives entirely in the URL of the report object, so the job is to get
     FILTER : ( ( REGION = 'Europe' ) )
     ```
 
+    A date parameter arrives as a display date and is rendered as a SAS date literal, the same as a date filter built inside Data Controller - `'12FEB1960'd` below, over the row it matches:
+
+    ![A date parameter rendered as a SAS date literal](img/va-report-filter-line.png)
+
     Something wrong shows the banner instead, with the cause and the fix - see [When a mapping cannot be used](#when-a-mapping-cannot-be-used) above.
 
 !!! note