refactor(tile-preload,ipc): collapse misc fallbacks + delete legacy (Phase 3.7d)
All 6 channels were already backed by strict tile:* handlers in tile-ipc.ts;
no new shims needed. Collapsed fallback branches to strict-only in
tile-preload.cts and deleted legacy ipcMain.handle blocks from ipc.ts:
- tile:window:set-visible-on-all-workspaces (was window-set-visible-on-all-workspaces)
- tile:oauth:start-loopback / tile:oauth:await-callback (were oauth-start-loopback / oauth-await-callback)
- tile:sync:sync-all (was sync-full)
- tile:screen:get-primary-display (was screen-get-primary-display)
- tile:session:save-space-workspaces (was save-space-workspaces)
Also removed now-unused createLoopbackServer import from ipc.ts.
Pre-audit confirmed zero legacy callers in app/ or features/.