feat(geoportal-v2): "Istoric" basemap — ESRI Wayback with date picker

Adds a 5th basemap option ("Istoric") that loads historical ESRI World
Imagery snapshots from the public Wayback service. Free, CORS-open,
193+ releases dating back to 2014; each release is identified by a
numeric id baked into the tile URL pattern.

How it works:
- wayback-catalog.ts fetches the public waybackconfig.json once per
  24h, parses each release's title for an ISO date, and exposes a
  newest-first list of { id, date, title, itemUrl }.
- BasemapSwitcher reveals a date dropdown beneath the basemap buttons
  when "Istoric" is selected. Auto-picks the latest release on first
  show; user can pick any past date.
- map-viewer rebuilds the MapLibre style when basemap=="wayback" with
  the user-picked release id patched into the raster source tiles[].

Tile URL format (WMTS, {z}/{y}/{x} not {z}/{x}/{y}):
  https://wayback.maptiles.arcgis.com/arcgis/rest/services
    /World_Imagery/WMTS/1.0.0/default028mm/MapServer
    /tile/<releaseId>/{z}/{y}/{x}

Esri's edge deduplicates identical tiles via 301 → another release id
(MapLibre/browser follows the redirect transparently), so picking a
random old date doesn't always show a different image when nothing
changed in that pixel — that's a feature of Wayback, not a bug.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/modules/geoportal/v2/wayback-catalog.ts

@@ -0,0 +1,92 @@
+// ESRI World Imagery Wayback — catalog helper for the "Satelit istoric"
+// basemap. Wayback is a free, public, CORS-open WMTS service that keeps
+// every snapshot of Esri's World Imagery layer back to 2014 (~193
+// releases as of 2026-05). Each release is identified by a numeric
+// `releaseId` baked into the tile URL:
+//
+//   https://wayback.maptiles.arcgis.com/arcgis/rest/services/World_Imagery
+//     /WMTS/1.0.0/default028mm/MapServer/tile/<releaseId>/{z}/{y}/{x}
+//
+// The catalog at /waybackconfig.json lists every release with its title
+// ("World Imagery (Wayback 2026-04-30)") which is the only place the
+// date lives. We parse the title to expose a sortable timeline.
+//
+// Caching: catalog is ~100 KB and updates monthly when Esri ships a new
+// release. Module-level cache + lazy fetch keeps the picker responsive
+// while still picking up new releases without a panel reload.
+
+export type WaybackRelease = {
+  /** Numeric release id baked into the tile URL (e.g. 49059). */
+  id: string;
+  /** Parsed release date — "2026-04-30" — from the item title. */
+  date: string;
+  /** Human-readable title verbatim from catalog. */
+  title: string;
+  /** Templated tile URL with {level}/{row}/{col} placeholders. */
+  itemUrl: string;
+};
+
+const CATALOG_URL =
+  "https://s3-us-west-2.amazonaws.com/config.maptiles.arcgis.com/waybackconfig.json";
+
+type CatalogEntry = {
+  itemID?: string;
+  itemTitle?: string;
+  itemURL?: string;
+};
+
+type Catalog = Record<string, CatalogEntry>;
+
+let cache: { at: number; data: WaybackRelease[] } | null = null;
+let inflight: Promise<WaybackRelease[]> | null = null;
+
+const CACHE_TTL_MS = 24 * 60 * 60 * 1000;
+
+function parseDate(title: string): string | null {
+  // "World Imagery (Wayback 2026-04-30)" → 2026-04-30
+  const m = /(\d{4}-\d{2}-\d{2})/.exec(title);
+  return m?.[1] ?? null;
+}
+
+/** Fetch + parse the Wayback catalog. Memoized 24h. */
+export async function loadWaybackReleases(): Promise<WaybackRelease[]> {
+  if (cache && Date.now() - cache.at < CACHE_TTL_MS) return cache.data;
+  if (inflight) return inflight;
+  inflight = (async () => {
+    try {
+      const res = await fetch(CATALOG_URL, { cache: "no-store" });
+      if (!res.ok) throw new Error(`wayback catalog ${res.status}`);
+      const json = (await res.json()) as Catalog;
+      const releases: WaybackRelease[] = [];
+      for (const [id, entry] of Object.entries(json)) {
+        if (!entry?.itemTitle || !entry?.itemURL) continue;
+        const date = parseDate(entry.itemTitle);
+        if (!date) continue;
+        releases.push({
+          id,
+          date,
+          title: entry.itemTitle,
+          itemUrl: entry.itemURL,
+        });
+      }
+      // Newest first — date string comparison works because ISO yyyy-mm-dd.
+      releases.sort((a, b) => (a.date < b.date ? 1 : -1));
+      cache = { at: Date.now(), data: releases };
+      return releases;
+    } finally {
+      inflight = null;
+    }
+  })();
+  return inflight;
+}
+
+/** Build the tile-URL template MapLibre expects for a given release id.
+ *  WMTS uses {z}/{y}/{x} order in the path (NOT {z}/{x}/{y}). */
+export function waybackTileUrl(releaseId: string): string {
+  return `https://wayback.maptiles.arcgis.com/arcgis/rest/services/World_Imagery/WMTS/1.0.0/default028mm/MapServer/tile/${releaseId}/{z}/{y}/{x}`;
+}
+
+/** Pick a reasonable default release: the most recent one. */
+export function latestWaybackRelease(releases: WaybackRelease[]): WaybackRelease | null {
+  return releases[0] ?? null;
+}