Implement Standalone Android App via Flutter WebView

- Configured `vite.config.ts` for relative base path support.
- Initialized `mobile_app` Flutter project with `webview_flutter`.
- Added `assets/www` to Flutter assets configuration.
- Implemented `mobile_app/lib/main.dart` with WebView and Bridge API integration (Water Level Slider).
- Updated `.gitignore` for Flutter artifacts.
- Successfully built APK artifacts.

Co-authored-by: kliffdafunkfacekilla-arch <239708976+kliffdafunkfacekilla-arch@users.noreply.github.com>

mobile_app/assets/www/modules/renderers/draw-features.js

@@ -0,0 +1,66 @@
+"use strict";
+
+function drawFeatures() {
+  TIME && console.time("drawFeatures");
+
+  const html = {
+    paths: [],
+    landMask: [],
+    waterMask: ['<rect x="0" y="0" width="100%" height="100%" fill="white" />'],
+    coastline: {},
+    lakes: {}
+  };
+
+  for (const feature of pack.features) {
+    if (!feature || feature.type === "ocean") continue;
+
+    html.paths.push(`<path d="${getFeaturePath(feature)}" id="feature_${feature.i}" data-f="${feature.i}"></path>`);
+
+    if (feature.type === "lake") {
+      html.landMask.push(`<use href="#feature_${feature.i}" data-f="${feature.i}" fill="black"></use>`);
+
+      const lakeGroup = feature.group || "freshwater";
+      if (!html.lakes[lakeGroup]) html.lakes[lakeGroup] = [];
+      html.lakes[lakeGroup].push(`<use href="#feature_${feature.i}" data-f="${feature.i}"></use>`);
+    } else {
+      html.landMask.push(`<use href="#feature_${feature.i}" data-f="${feature.i}" fill="white"></use>`);
+      html.waterMask.push(`<use href="#feature_${feature.i}" data-f="${feature.i}" fill="black"></use>`);
+
+      const coastlineGroup = feature.group === "lake_island" ? "lake_island" : "sea_island";
+      if (!html.coastline[coastlineGroup]) html.coastline[coastlineGroup] = [];
+      html.coastline[coastlineGroup].push(`<use href="#feature_${feature.i}" data-f="${feature.i}"></use>`);
+    }
+  }
+
+  defs.select("#featurePaths").html(html.paths.join(""));
+  defs.select("#land").html(html.landMask.join(""));
+  defs.select("#water").html(html.waterMask.join(""));
+
+  coastline.selectAll("g").each(function () {
+    const paths = html.coastline[this.id] || [];
+    d3.select(this).html(paths.join(""));
+  });
+
+  lakes.selectAll("g").each(function () {
+    const paths = html.lakes[this.id] || [];
+    d3.select(this).html(paths.join(""));
+  });
+
+  TIME && console.timeEnd("drawFeatures");
+}
+
+function getFeaturePath(feature) {
+  const points = feature.vertices.map(vertex => pack.vertices.p[vertex]);
+  if (points.some(point => point === undefined)) {
+    ERROR && console.error("Undefined point in getFeaturePath");
+    return "";
+  }
+
+  const simplifiedPoints = simplify(points, 0.3);
+  const clippedPoints = clipPoly(simplifiedPoints, 1);
+
+  const lineGen = d3.line().curve(d3.curveBasisClosed);
+  const path = round(lineGen(clippedPoints)) + "Z";
+
+  return path;
+}