Fix mobile map API calls by using relative URLs

API base was hardcoded to localhost:3001, which fails on mobile
devices. Use relative paths instead and configure shadow-cljs
dev-http to proxy API requests to the backend in development.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: ahmed-machine

shadow-cljs.edn

@@ -4,7 +4,9 @@
                 [re-frame "1.3.0"]
                 [cljs-ajax "0.8.4"]]
 
- :dev-http {8280 "public"}
+ :dev-http {8280 {:root "public"
+                  :proxy-url "http://localhost:3001"
+                  :use-index-files true}}
 
  :builds
  {:app {:target :browser

src/howfar/api.cljs

@@ -2,7 +2,7 @@
   (:require [ajax.core :as ajax]
             [re-frame.core :as rf]))
 
-(def api-base "http://localhost:3001")
+(def api-base "")
 
 (defn api-url [path]
   (str api-base path))