Closes out the 13-phase menu redesign. Three parts:
1. Post-sync merge summary: the pull poller now keeps the
`ConflictReport`s the merge produces (previously discarded) in a new
`SyncConflictLog` resource and toasts "Synced — N conflicts, kept
newer values" when a merge wasn't clean. No wire changes — the
server-side `SyncResponse.conflicts` field already existed.
2. Account tab detail: a per-field conflict list under the sync row
("win_streak_current — this device: 3 / server: 5") plus a
clean-merge caption, so the last merge is always inspectable.
3. Local data export/import: new `solitaire_data::transfer` module —
one versioned JSON bundle (settings, stats, achievements, progress)
written atomically next to the other saves, with a version-gated
loader that surfaces every failure instead of defaulting. Account
tab grows an Export/Import button pair (desktop+Android only); the
handler runs in `Last`, off the annotated Update spine. Import
rewrites the live resources, persists via the existing save fns,
and fires SettingsChangedEvent so appliers react normally.
Tests: bundle round-trip/version-gate/missing-file in solitaire_data;
ECS-level export→import round trip and failed-import-warns in
settings_plugin. Gate: workspace tests green, clippy -D warnings clean.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
funman300