feat: builder-style InputSpec API, prefill plumbing, and port forward fix

- Add addKey() and add() builder methods to InputSpec with InputSpecTools
- Move OuterType to last generic param on Value, List, and all dynamic methods
- Plumb prefill through getActionInput end-to-end (core → container-runtime → SDK)
- Filter port_forwards to enabled addresses only
- Bump SDK to 0.4.0-beta.50

web/projects/ui/src/app/routes/portal/routes/services/modals/action-input.component.ts

@@ -148,6 +148,7 @@ export class ActionInputModal {
       this.api.getActionInput({
         packageId: this.pkgInfo.id,
         actionId: this.actionId,
+        prefill: this.context.data.prefill ?? null,
       }),
     ).pipe(
       map(res => {