Vehicle save: false-success over stale table + invisible list-refresh error

[dynnamitt]

Refetch-hardening + dedup across the three sidebar surfaces — all now ?selected= editors sharing the same doFetch / handleSave / handleDeactivate block:

• VehicleType — pattern landed in feat(vehicle-types): GraphQL save via createOrUpdateVehicleType (#109) #114, fix(#122): doFetch return regression surfaced by e2e org-rebuild (#117) #125.
• Vehicle — real GQL createOrUpdateVehicle (highest-stakes).
• DeckPlan — now sidebar-based too (was route-based); inline-fixed to the same shape in a4d9372 (more uniform table ux across all 3 entity pages #129).

Bugs (same shape, repeated per surface)

• False-success over stale table — handleSave/handleDeactivate set the green "saved" flag before await onSaved, so a committed save whose post-save refetch fails still shows success over a stale table. useVehicles.doFetch swallows fetch errors; VehicleDetails.handleSave has no try/catch. src/data/vehicles/hooks/useVehicles.ts, src/data/vehicles/components/VehicleDetails.tsx:72
• Invisible list error — list error is hidden when data is non-empty, so non-save refetch failures (e.g. filterParam change after an Autosys import) silently leave a stale table. src/pages/GenericDataViewPage.tsx
• Test gap — VT refetch-fail e2e asserts warning + no success, but not the catch-path re-baseline (form not dirty / mode→view) → a GenericDataViewPage — sort or switch page must collapse details (with dirty-guard) #91-class discard-dialog regression could slip. e2e-tests/no-auth/vehicle-type-sidebar.spec.ts

Lift (dedup destination)

• src/utils/translateFetchError.ts — generic of the error switch (from fetchVehiclesAndApply.ts).
• src/hooks/useEntityListFetch.ts — generic gate / loading / error / refetch hook; migrate useVehicleTypes, useDeckPlans, useVehicles (latter deletes fetchVehiclesAndApply.ts + test).
• useMutationOutcome({ mutate, onSaved }) — owns the success flag (set after await onSaved), tags { outcome: 'mutation-error' | 'refetch-error' | 'ok' } for severity routing, and owns the snackbar render slot (omitting it = compile error). Dissolves the ~19-line handleSave/handleDeactivate copy in all three Details files down to ~5 lines each, plus commitSave (now unused — delete).

Status

• useVehicleTypes — good shape (fix(#122): doFetch return regression surfaced by e2e org-rebuild (#117) #125).
• useDeckPlans — same shape (a4d9372, more uniform table ux across all 3 entity pages #129).
• useVehicles — still setter-injection via fetchVehiclesAndApply, no rethrow.
• Feature/add disable option #131 reproduces the handleDeactivate copy a third time → land the lift first, then re-implement Feature/add disable option #131 on top (~5 lines each).

Refs: #114, #91, #130 (closed as dup), #131.