Harden scoped cleanup for agent timeout, observer listeners, and composition runners

[danielbdyer]

Motivation

• Ensure agent LLM calls, Playwright page listeners, and composition-level resources are reliably finalized under interruption/timeouts by using Effect scoped lifecycle primitives.
• Replace ad-hoc promise cancellation and loose listener registration with structured Effect.acquireRelease / Effect.scoped so fibers and resources are not leaked during timeouts or cancellations.
• Normalize the agent timeout semantics so timeouts and interpretation cancellation share the same scoped-fiber cancellation model instead of racing raw promises.

Description

• Reworked agent timeout wiring: withAgentTimeout now invokes withAgentTimeoutEffect inside Effect.scoped, and withAgentTimeoutEffect races a scoped interpretation fiber against a timeout using Effect.forkScoped, Fiber.join, and Effect.raceFirst to return the deterministic fallback on timeout (lib/application/agent-interpreter-provider.ts).
• Wrapped Playwright screen observation in Effect.scoped and registered the page close listener with Effect.acquireRelease so the listener is always removed on scope exit and observations fail-fast if the page is already closed (lib/infrastructure/observation/playwright-screen-observer.ts).
• Scoped composition boundaries by running the runtime scenario runner body under Effect.scoped and returning a scoped provide in the local services composition so downstream scoped resources are finalized reliably (lib/composition/local-runtime-scenario-runner.ts, lib/composition/local-services.ts).
• Minor imports/shape adjustments to support Fiber/scoped forks and to preserve existing fallback behavior on errors or timeouts (lib/application/agent-interpreter-provider.ts).

Testing

• Ran the focused lifecycle stress tests with Playwright: npm test -- tests/agent-resource-lifecycle.spec.ts and all tests in that file passed (4/4) after the changes.
• Ran npm run typecheck which reported pre-existing unrelated diagnostics in other modules, so typecheck did not pass end-to-end; the failures are unrelated to the lifecycle changes.
• Verified the repository diff includes only the intended files: lib/application/agent-interpreter-provider.ts, lib/infrastructure/observation/playwright-screen-observer.ts, lib/composition/local-runtime-scenario-runner.ts, and lib/composition/local-services.ts.

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Codex Task