Add progressive web app companion for cross-platform access

Vite + TypeScript PWA that mirrors the Android app's core features:
- Pre-processed shelter data (build-time UTM33N→WGS84 conversion)
- Leaflet map with shelter markers, user location, and offline tiles
- Canvas compass arrow (ported from DirectionArrowView.kt)
- IndexedDB shelter cache with 7-day staleness check
- Service worker with CacheFirst tiles and precached app shell
- i18n for en, nb, nn (ported from Android strings.xml)
- iOS/Android compass handling with low-pass filter
- Respects user map interaction (no auto-snap on pan/zoom)
- Build revision cache-breaker for reliable SW updates

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pwa/node_modules/terser/lib/utils/first_in_statement.js

@@ -0,0 +1,53 @@
+import {
+    AST_Binary,
+    AST_Conditional,
+    AST_Chain,
+    AST_Dot,
+    AST_Object,
+    AST_Sequence,
+    AST_Statement,
+    AST_Sub,
+    AST_UnaryPostfix,
+    AST_PrefixedTemplateString
+} from "../ast.js";
+
+// return true if the node at the top of the stack (that means the
+// innermost node in the current output) is lexically the first in
+// a statement.
+function first_in_statement(stack) {
+    let node = stack.parent(-1);
+    for (let i = 0, p; p = stack.parent(i); i++) {
+        if (p instanceof AST_Statement && p.body === node)
+            return true;
+        if ((p instanceof AST_Sequence && p.expressions[0] === node) ||
+            (p.TYPE === "Call" && p.expression === node) ||
+            (p instanceof AST_PrefixedTemplateString && p.prefix === node) ||
+            (p instanceof AST_Dot && p.expression === node) ||
+            (p instanceof AST_Sub && p.expression === node) ||
+            (p instanceof AST_Chain && p.expression === node) ||
+            (p instanceof AST_Conditional && p.condition === node) ||
+            (p instanceof AST_Binary && p.left === node) ||
+            (p instanceof AST_UnaryPostfix && p.expression === node)
+        ) {
+            node = p;
+        } else {
+            return false;
+        }
+    }
+}
+
+// Returns whether the leftmost item in the expression is an object
+function left_is_object(node) {
+    if (node instanceof AST_Object) return true;
+    if (node instanceof AST_Sequence) return left_is_object(node.expressions[0]);
+    if (node.TYPE === "Call") return left_is_object(node.expression);
+    if (node instanceof AST_PrefixedTemplateString) return left_is_object(node.prefix);
+    if (node instanceof AST_Dot || node instanceof AST_Sub) return left_is_object(node.expression);
+    if (node instanceof AST_Chain) return left_is_object(node.expression);
+    if (node instanceof AST_Conditional) return left_is_object(node.condition);
+    if (node instanceof AST_Binary) return left_is_object(node.left);
+    if (node instanceof AST_UnaryPostfix) return left_is_object(node.expression);
+    return false;
+}
+
+export { first_in_statement, left_is_object };