Use correct variable for API Origin

Previously we were reading `config.source` and then removing the
trailing slash. However, this doesn't include the port, which we use
when running locally. `config['puter.api_origin']` is actually what we
want, which does have the port if it's set, and doesn't include the
trailing slash either.

src/main_puter.js

@@ -58,10 +58,7 @@ window.main_shell = async () => {
     if ( config['puter.auth.token'] ) {
         await puterSDK.setAuthToken(config['puter.auth.token']);
     }
-    const source_without_trailing_slash =
-        (config.source && config.source.replace(/\/$/, ''))
-        || 'https://api.puter.com';
-    await puterSDK.setAPIOrigin(source_without_trailing_slash);
+    await puterSDK.setAPIOrigin(config['puter.api_origin']);
 
     const ptt = new XDocumentPTT();
     await launchPuterShell(new Context({

src/puter-shell/main.js

@@ -76,10 +76,7 @@ export const launchPuterShell = async (ctx) => {
     const sdkv2 = globalThis.puter;
     if ( ctx.platform.name !== 'node' ) {
         await sdkv2.setAuthToken(config['puter.auth.token']);
-        const source_without_trailing_slash =
-            (config.source && config.source.replace(/\/$/, ''))
-            || 'https://api.puter.com';
-        await sdkv2.setAPIOrigin(source_without_trailing_slash);
+        await sdkv2.setAPIOrigin(config['puter.api_origin']);
     }
 
     // const commandProvider = new BuiltinCommandProvider();