drop the two apps API wrappers the socket-driven update flow orphaned

[atomantic]

Summary

• client/src/services/api.deadExports.test.js fails on any full-mode client run with caller-less wrappers: apiApps.js:getPreferredSelfRestartOrigin, apiApps.js:pullAndUpdateApp. main's CI is green only because the run planner scopes tests to changed files, so this blocks unrelated PRs (e.g. fix: publish the endpoint guard through aiToolkit's public barrel #5625, a server-only change).
• Root cause: 2e996e4d2 moved RepositorySourcePanel.jsx onto the socket-driven useAppOperation hook. Its only remaining api.* calls are getAppRepositorySources and syncAppRepositoryFork.
• Deleted (not un-exported) both symbols: neither is referenced inside apiApps.js — handleSelfRestart does not call getPreferredSelfRestartOrigin, so there is no intra-module use to preserve.
• Removed the now-unused import { getNetworkExposure } from './apiSystem.js' and its vi.mock/vi.hoisted scaffolding in apiApps.test.js. No cascade: getNetworkExposure still has live callers in NetworkExposureWidget.jsx and Instances.jsx.
• Test cleanup: dropped the dead getPreferredSelfRestartOrigin describe block, the two dead vi.fn() mocks in RepositorySourcePanel.test.jsx, and retargeted the vacuous expect(api.pullAndUpdateApp).not.toHaveBeenCalled() at the live surface (useAppOperation(...).startUpdate) so the "Sync fork must not kick off an update" regression is still covered.
• No barrel or README change needed — api.js re-exports apiApps.js with export *, and the services README catalogs modules, not individual exports.

POST /api/apps/:id/update consumer finding

• The server route (server/routes/apps/lifecycle.js:240) is left untouched — removing it is out of scope.
• It now has no client caller. The live update path is the Socket.IO app:update event (server/sockets/apps.js:91), which useAppOperation.js:162 emits; both handlers call the same appUpdater.updateApp.
• Remaining references are its own route test (server/routes/apps/lifecycle.test.js:401), the generated route catalog, and a historical changelog entry. No sockets, palette/voice manifest entries, or scripts reach it.

Test plan

• client && npx vitest run src/services/api.deadExports.test.js src/services/apiApps.test.js src/components/apps/tabs/RepositorySourcePanel.test.jsx — 3 files, 13 tests passed.
• Full client suite client && npm run test:ci — 861 passed | 1 skipped (862 files), 10756 passed | 2 skipped (10758 tests), 142s. Zero failures; the dead-export guard is green in full mode, which is the point of the fix.
• client && npm run build — clean.

Fixes #5848