feat(street-level): KartaView's SINCE is its upload date, noted in the panel

KartaView's server filters by upload date only, so SINCE goes by it
throughout for KartaView: the lines (as before), the photo a click opens
and the cones, the cut-off taken as its UTC day as KartaView's startDate
(passesKartaViewFilter). Providers may declare sinceBasis: 'upload'
(validated); while one is lit the panel shows "KartaView: by upload date"
under the SINCE slider, read out with it. The gate checks the note, and
step 13's picks get 60 s on a loaded machine.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/layers/streetLevel/registry.js

@@ -24,6 +24,7 @@ export function filtersOf(provider) {
  * @property {Array<'pano'|'since'>} [filters]   Filters it honours (default both).
  * @property {{noun: string, action: string}} [coverageLabel]   How the panel counts its lines and says what a click does (default: sequences, "click a line for its photos").
  * @property {boolean} [highlightsSequence]   Its lines show the selected sequence (default true; the legend's "Selected" needs one).
+ * @property {'capture'|'upload'} [sinceBasis]   What SINCE compares (default 'capture'); 'upload' puts a note under the slider while the provider is lit.
  * @property {(context: ProviderContext) => ProviderInstance} create
  *
  * @typedef {object} ProviderContext   Handed to `create()` once by the core.
@@ -160,6 +161,14 @@ export function validateProviders(providers) {
       throw new TypeError(
         `Street Level provider ${label}: filters must list ${IMAGERY_FILTERS.join(' or ')}`,
       );
+    if (
+      provider.sinceBasis !== undefined &&
+      provider.sinceBasis !== 'capture' &&
+      provider.sinceBasis !== 'upload'
+    )
+      throw new TypeError(
+        `Street Level provider ${label}: sinceBasis must be 'capture' or 'upload'`,
+      );
     ids.add(provider.id);
     prefixes.push(provider.pickPrefix);
   }