fix: 7 bug fixes + port config with auto-restart

- HTTPException import added (was causing 500 on missing dashboard)
- game_manager.remove_plugin() restored (was AttributeError)
- api.js checks HTTP status codes, fails fast on errors
- sidebar game highlight only matches selected gameId
- scene resize handler uses stored canvas dims (was NaN)
- forwarder socket properly closed on listener stop
- telemetry port: use_unified_port toggle, off = per-game port, auto-restart on switch

static/js/api.js

@@ -1,33 +1,24 @@
 const API = {
     _base: '/api',
 
-    async get(path) {
-        const res = await fetch(`${this._base}${path}`);
+    async _req(method, path, body) {
+        const opts = { method };
+        if (body) {
+            opts.headers = { 'Content-Type': 'application/json' };
+            opts.body = JSON.stringify(body);
+        }
+        const res = await fetch(`${this._base}${path}`, opts);
+        if (!res.ok) {
+            const text = await res.text().catch(() => '');
+            throw new Error(`${method} ${path} ${res.status}: ${text.slice(0, 200)}`);
+        }
         return res.json();
     },
 
-    async post(path, data) {
-        const res = await fetch(`${this._base}${path}`, {
-            method: 'POST',
-            headers: { 'Content-Type': 'application/json' },
-            body: JSON.stringify(data),
-        });
-        return res.json();
-    },
-
-    async put(path, data) {
-        const res = await fetch(`${this._base}${path}`, {
-            method: 'PUT',
-            headers: { 'Content-Type': 'application/json' },
-            body: JSON.stringify(data),
-        });
-        return res.json();
-    },
-
-    async del(path) {
-        const res = await fetch(`${this._base}${path}`, { method: 'DELETE' });
-        return res.json();
-    },
+    async get(path) { return this._req('GET', path); },
+    async post(path, data) { return this._req('POST', path, data); },
+    async put(path, data) { return this._req('PUT', path, data); },
+    async del(path) { return this._req('DELETE', path); },
 
     async getStatus() { return this.get('/status'); },
     async getConfig() { return this.get('/config'); },