fix: support outputFromObservable() from @angular/core/rxjs-interop

[ashley-hunter]

Problem

Properties declared with outputFromObservable() from @angular/core/rxjs-interop were silently dropped from the compiled output metadata. The Angular runtime uses the outputs: {} object in ɵɵdefineComponent/ɵɵdefineDirective to wire up event bindings — missing entries mean parent components can never bind to those outputs.

Example that was broken:

readonly queryChanged = outputFromObservable(
  this.queryEditorService.latestParsedDataprimeQuery$.pipe(
    skip(1),
    debounceTime(300),
  ),
);

Root cause

try_parse_signal_output in property_decorators.rs only matched the identifier "output". outputFromObservable was never recognised, so its properties returned None and were excluded from the outputs metadata.

Fix

Extend try_parse_signal_output to detect both output() and outputFromObservable() (including namespaced forms like core.outputFromObservable()). The key behavioural difference is argument position: output() takes options at index 0, while outputFromObservable(observable, options?) takes them at index 1. The observable expression itself is irrelevant for metadata extraction and is ignored.

Tests

5 new unit tests added via TDD (red → green):

• Simple arg — outputFromObservable(new EventEmitter<string>())
• Property reference — outputFromObservable(this.service.obs$)
• Piped observable — outputFromObservable(this.service.obs$.pipe(skip(1), debounceTime(300))) (the reported real-world case)
• Alias — outputFromObservable(new EventEmitter(), { alias: 'clicked' })
• Mixed — class using both output() and outputFromObservable() together

Also adds an e2e compare fixture (inputs-outputs/output-from-observable) covering all four scenarios so the output can be validated against the official Angular compiler.

Coverage

All 8 Angular initializer API functions are now handled by the Rust compiler. outputFromObservable was the only missing one.