refactor(async): add scoped resource lifecycle

[beruro]

Problem

The legacy async-data helper does not make scope changes, stale completions, unmount cancellation, or hidden-window polling ownership explicit, allowing old requests and duplicate timers to outlive their consumer.

Solution

• Introduce a scoped async-resource lifecycle with stale-result fencing and abort-on-scope-change/unmount behavior.
• Add visibility-aware polling that pauses while hidden and resumes without duplicate timers.
• Add shared latest-task and polling primitives with focused lifecycle tests.
• Include architecture, UI-consistency, and performance-guard audit records.
• Keep this foundation isolated from the consumer migrations in refactor(data): scope async resource consumers #563 and runtime bounds in perf(runtime): bound caches, scans, and background work #564.

Potential risks

• Incorrect scope keys could retain stale data or cancel valid work; consumers must provide authoritative identity/resource scope.
• Visibility-paused resources must revalidate once on return without overlapping an existing request.
• refactor(data): scope async resource consumers #563 and perf(runtime): bound caches, scans, and background work #564 depend on this PR and should be retargeted only after this foundation lands. Rollback is a normal revert; there is no schema, wire, dependency, or persistence migration.

Verification

Validated locally after merging current develop (017fb9afa) into head 8618af370 without conflicts:

• pnpm install --frozen-lockfile — PASS. The optional legacy node-sass native postinstall could not build under the local Node/Python combination, but installation completed and repository checks ran normally.
• pnpm exec vitest run src/hooks/async/useAsyncResource.test.ts src/hooks/async/useVisibilityPolledData.test.ts src/util/core/__tests__/latestScopedTask.test.ts src/util/core/__tests__/visibilityAwarePoll.test.ts — PASS, 4 files / 18 tests.
• pnpm typecheck — PASS.
• git diff --cached --check before the merge commit — PASS.

Published GitHub CI on head 8618af370 is fully green: Frontend typecheck/lint/test, Rust clippy, and AI attribution all passed.