refactor(iot-hub): remove positional output variable support from device install wizard

Drop ${step1.id}, ${step2.name} etc. positional variable resolution.
Only named entity outputs (${device.id}, ${dashboard.name}) are supported.
Updated spec to reflect the simplified resolution priority.

docs/superpowers/specs/2026-04-02-transport-variables-design.md

@@ -0,0 +1,72 @@
+# Transport Variables in Device Install Templates — Design Spec
+
+## Goal
+
+Add transport host/port variables to the device install wizard's template resolution so that post-install instructions and entity templates can reference the platform's configured transport endpoints (e.g., `${mqtt.host}`, `${coap.port}`).
+
+## Variables
+
+All 6 transport protocols are supported:
+
+| Variable | Example value | Source |
+|----------|--------------|--------|
+| `${http.host}` | `demo.thingsboard.io` | Admin settings `connectivity.http.host` |
+| `${http.port}` | `8080` | Admin settings `connectivity.http.port` |
+| `${https.host}` | `demo.thingsboard.io` | Admin settings `connectivity.https.host` |
+| `${https.port}` | `443` | Admin settings `connectivity.https.port` |
+| `${mqtt.host}` | `demo.thingsboard.io` | Admin settings `connectivity.mqtt.host` |
+| `${mqtt.port}` | `1883` | Admin settings `connectivity.mqtt.port` |
+| `${mqtts.host}` | `demo.thingsboard.io` | Admin settings `connectivity.mqtts.host` |
+| `${mqtts.port}` | `8883` | Admin settings `connectivity.mqtts.port` |
+| `${coap.host}` | `demo.thingsboard.io` | Admin settings `connectivity.coap.host` |
+| `${coap.port}` | `5683` | Admin settings `connectivity.coap.port` |
+| `${coaps.host}` | `demo.thingsboard.io` | Admin settings `connectivity.coaps.host` |
+| `${coaps.port}` | `5684` | Admin settings `connectivity.coaps.port` |
+
+These variables are available in all template and instruction files, alongside form values and entity outputs.
+
+## Data Source
+
+Frontend fetches from existing admin settings API:
+```
+GET /api/admin/settings/connectivity
+```
+
+Returns `DeviceConnectivitySettings` — a `Record<DeviceConnectivityProtocol, DeviceConnectivityInfo>` where each entry has `{ enabled, host, port }`.
+
+The `AdminService.getAdminSettings<DeviceConnectivitySettings>('connectivity')` method and `DeviceConnectivitySettings` model already exist in the codebase.
+
+## Resolution Priority
+
+The `resolveVariables()` function checks sources in this order:
+1. Form field values (`formValues[key]`) — e.g., `${deviceName}`
+2. Transport connectivity (`transportVars[key]`) — e.g., `${mqtt.host}`
+3. Named entity outputs (`entityOutputs[alias].prop`) — e.g., `${device.id}`
+
+Transport variables use dot notation (`mqtt.host`) which currently falls through to entity output resolution. By adding a transport lookup before entity outputs, we ensure `${mqtt.host}` resolves to the transport config rather than looking for a non-existent entity alias called `mqtt`.
+
+## Changes
+
+**Single file:** `ui-ngx/src/app/modules/home/pages/iot-hub/device-install-dialog/device-install-dialog.component.ts`
+
+1. Inject `AdminService` (from `@core/http/admin.service`)
+2. In `ngOnInit`, after ZIP parsing, fetch connectivity settings and flatten to `Record<string, string>`:
+   ```
+   { 'http.host': '...', 'http.port': '8080', 'mqtt.host': '...', 'mqtt.port': '1883', ... }
+   ```
+3. In `resolveVariables()`, check the transport map for dot-notation keys before falling through to entity outputs
+
+**No backend changes. No new models. No new endpoints.**
+
+## Example Usage in Templates
+
+Post-install instruction (`post-install.md`):
+```markdown
+#define THINGSBOARD_SERVER  "${mqtt.host}"
+#define THINGSBOARD_PORT    ${mqtt.port}
+```
+
+Integration template (`integration.json`):
+```json
+{"baseUrl": "${http.host}:${http.port}"}
+```

ui-ngx/src/app/modules/home/components/iot-hub/device-install-dialog/device-install-dialog.component.ts

@@ -96,7 +96,6 @@ export class TbDeviceInstallDialogComponent extends DialogComponent<TbDeviceInst
   // Variable resolution state
   formValues: Record<string, any> = {};
   entityOutputs = new Map<string, EntityStepOutput>();
-  positionalOutputs = new Map<number, EntityStepOutput>();
 
   constructor(
     protected store: Store<AppState>,
@@ -241,13 +240,6 @@ export class TbDeviceInstallDialogComponent extends DialogComponent<TbDeviceInst
         if (output && prop in output) {
           return String((output as any)[prop]);
         }
-        const m = alias.match(/^step(\d+)$/);
-        if (m) {
-          const pos = this.positionalOutputs.get(parseInt(m[1], 10));
-          if (pos && prop in pos) {
-            return String((pos as any)[prop]);
-          }
-        }
       }
       return '${' + key + '}';
     });
@@ -258,7 +250,6 @@ export class TbDeviceInstallDialogComponent extends DialogComponent<TbDeviceInst
   private startWizard(): void {
     this.formValues = {};
     this.entityOutputs.clear();
-    this.positionalOutputs.clear();
     this.passwordVisible = {};
     this.buildWizardSteps();
     this.wizardStarted = true;
@@ -383,12 +374,6 @@ export class TbDeviceInstallDialogComponent extends DialogComponent<TbDeviceInst
         if (alias) {
           this.entityOutputs.set(alias, output);
         }
-        const rawSteps = this.packageInfo.installSteps[this.selectedConnectivity] || [];
-        const stepIdx = rawSteps.indexOf(ep.step);
-        if (stepIdx >= 0) {
-          this.positionalOutputs.set(stepIdx + 1, output);
-        }
-
         // Re-resolve names of remaining pending steps
         for (const remaining of ws.entitySteps) {
           if (remaining.status === 'pending') {