Check a saved custom answer in the resolved history

The progressive custom answer test closes the resolved history, then
looked for the saved Scope card among outstanding decisions. On 115df25
and b52437b it passed 10 of 10 only because the filled answer never
reached the server: Save was rejected with "Scope requires a custom
answer" and the unsaved card stayed put. Since 6e1b405 saves it, the
card moves into the closed history, and the assertion passed in 4 of 10
runs, only when it polled before the plan update arrived.

Open the resolved history and check the saved answer and its resolver.

Assistant-model: Claude Opus 5.5
Assistant-workflow: goal (run 98acf681-3730-4957-b885-0d70e0e6b32a)
Assistant-verification: original e2e test repeat-each 10 failed: 4/10 passed at 6e1b405, where Save succeeded; it passed 10/10 on 115df25 and b52437b only because WebSocket logs showed the server rejecting Save with "Scope requires a custom answer"
Assistant-verification: fail-before/pass-after passed: the corrected test failed 10/10 on b52437b ("2 resolved" never appeared; card showed the rejection alert) and passed 20/20 at 6e1b405 after a fresh client build
Assistant-verification: bun run e2e passed: 236 passed, 0 failed
Assistant-verification: bun test passed: 1732 pass, 2 PostgreSQL skips, 0 fail, 7402 assertions across 196 files
Assistant-verification: bun run types passed: all workspaces and E2E
Assistant-verification: bun run fix passed: no change to tracked files; one existing lint warning
Assistant-verification: bun run ci failed: dprint flagged only four untracked .atomic/todos files; dprint check excluding .atomic, oxlint, token, type-scale and design checks then passed
User-preference: "Atomic's SDK is the runtime and the host supplies human input; Chopin implements HostInput rather than intercepting tools"
User-preference: "In local mode the Planner may run as a full Atomic session so workflows run inside Chopin with questions in Decisions"
Co-authored-by: Alex Lavaee <lavaman131@github.com>