fix(mobile): keep comment authors and threads when the phone rewrites a sidecar

[adibhanna]

Between the 1.1.16 pin and a3e638fc, desktop vault.ts replaced its private comment normalizer with the shared @shared/note-comments, which keeps the app core 2.46 author and parentId fields. The shell's MobileVault.writeNoteComments still rebuilt each record from a fixed field list, and app-core hands over the whole list on every comment action, so one reply, resolve, or delete on the phone flattened every thread and dropped every name the desktop or an assistant had written into the sidecar.

src/bridge/vault-fs.ts now reads and writes the sidecar through the shared normalizer, as desktop does. Same fix as iPhone 1.9.8.

Also points the 1.1.18 pack at iPhone 1.9.8 (build 19): the iOS release was renumbered from 1.9.9, since the pin-only 1.9.8 never shipped.

Verified: npm run typecheck clean at the pin, npm run build clean, npm test 50/50. MobileVault cannot run under node --test, and the fix was not re-run on the AVD.