feat(approvals): govern once and run scopes

[Bindy-lbb]

Closes #401

Implements engine-declared, source-bound approval scopes.

• validates approval-scope-offer.v1 at the engine and persisted-turn boundaries
• verifies the SHA-256 binding against approval, source run, action, and expiry before allowing run
• persists and replays the selected scope idempotently
• exposes only server-verified choices in both approval UI entry points and shows the effective audit boundary
• adds protocol, service, expiry/replay, renderer, and documentation coverage

Verification:

• npm run build
• node --test apps/server/dist/test/approval.test.js apps/server/dist/test/approvals-center.test.js
• npm run test:renderer -- approvals-state.test.tsx approval-queue.test.tsx
• npm run typecheck:renderer
• npm run typecheck:ui

[waterbro-8]

Review — Request changes

Exact head de85478fab60. MERGEABLE vs main after the #313 rebase, but required verify is red.

Blocking: packages/shared/src/approval-scope.ts is exported from the shared barrel, but dist/approval-scope.js is not on SHARED_RUNTIME_FILES in apps/desktop/packaging/runtime-layout.cjs.

Ubuntu Node 24 fails:

shared runtime inventory must be updated explicitly when source modules change
packages/shared/dist/index.js imports unpackaged dist/approval-scope.js

Same class of miss as #405 (approval-preview.js). Add dist/approval-scope.js to the allowlist (and any other new shared dist files this PR introduces), then re-run verify.

Layout-parity / unpacked-smoke reds look like fallout from that unpackaged module, not a separate product issue.

Not product验收. Not mergeable until packaging + Node 24 are green.

[waterbro-8]

Review — Approve (code, not 产品验收)

Exact head fb37f8f81f29. MERGEABLE. CI 11/11 green.

The previous blocker is fixed: dist/approval-scope.js is on SHARED_RUNTIME_FILES next to approval-preview.js. Verify (ubuntu/mac, unpacked smoke, layout parity) is green.

Scope remains engine-declared approval-scope-offer.v1 with SHA-256 binding; not product验收. Not auto-merge.