test(frontend): replay real messages instead of hand-built state literals (WP-70)

Every machine spec redefined its own throwaway fixture helper (editing1/2/3,
editingWith), hardcoding fields like errors: {} that assert against shapes
the reducer may never actually produce. given(reduce, initial)(...msgs)
(libs/shared/src/testing/machine.ts) replaces them by replaying real Msgs
through the real reduce, so a fixture is provably reachable. Adds the same
idiom for value objects (unwrapOk) and RemoteData (loading/success/failure),
plus intake.acceptance.spec.ts as a worked full-journey example.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/ssp/tsconfig.app.json

@@ -7,5 +7,5 @@
     "types": ["@angular/localize"]
   },
   "include": ["src/**/*.ts"],
-  "exclude": ["src/**/*.spec.ts", "src/**/*.stories.ts"]
+  "exclude": ["src/**/*.spec.ts", "src/**/*.stories.ts", "src/**/*.testing.ts"]
 }