Add settings page for managing forecasting API key and URL via UI

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

frontend/node_modules/recharts/es6/util/LRUCache.js

@@ -0,0 +1,37 @@
+function _defineProperty(e, r, t) { return (r = _toPropertyKey(r)) in e ? Object.defineProperty(e, r, { value: t, enumerable: !0, configurable: !0, writable: !0 }) : e[r] = t, e; }
+function _toPropertyKey(t) { var i = _toPrimitive(t, "string"); return "symbol" == typeof i ? i : i + ""; }
+function _toPrimitive(t, r) { if ("object" != typeof t || !t) return t; var e = t[Symbol.toPrimitive]; if (void 0 !== e) { var i = e.call(t, r || "default"); if ("object" != typeof i) return i; throw new TypeError("@@toPrimitive must return a primitive value."); } return ("string" === r ? String : Number)(t); }
+/**
+ * Simple LRU (Least Recently Used) cache implementation
+ */
+export class LRUCache {
+  constructor(maxSize) {
+    _defineProperty(this, "cache", new Map());
+    this.maxSize = maxSize;
+  }
+  get(key) {
+    var value = this.cache.get(key);
+    if (value !== undefined) {
+      this.cache.delete(key);
+      this.cache.set(key, value);
+    }
+    return value;
+  }
+  set(key, value) {
+    if (this.cache.has(key)) {
+      this.cache.delete(key);
+    } else if (this.cache.size >= this.maxSize) {
+      var firstKey = this.cache.keys().next().value;
+      if (firstKey != null) {
+        this.cache.delete(firstKey);
+      }
+    }
+    this.cache.set(key, value);
+  }
+  clear() {
+    this.cache.clear();
+  }
+  size() {
+    return this.cache.size;
+  }
+}