BuildMerkleTrie runs a reader that pages pending hashes into a buffered channel and a writer that drains it into the merkle trie. The writer stops on any per-chunk error, most reachably the duplicate-hash rejection a catchpoint provider can trigger by repeating a balance record. Nothing told the reader, whose send was unconditional, so it parked forever on a full queue and wg.Wait never returned: BuildMerkleTrie hung instead of returning the error it had already produced, leaking both goroutines and the snapshot transaction, and leaving the node wedged in catchup until restarted.

Derive a worker context, cancel it from a defer in the writer so every exit path signals, and make the reader's send select on it. The reader reports no error of its own when it unwinds that way, so the writer's error is what reaches the caller.

Also names the queue depth, which the regression test needs in order to stage enough chunks to fill the queue.

feat: registry funding panel sizing worst-case MBR for both registries

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

The previous commit gated the top-up on balances and stopped there. The
re-review found the gap that leaves, and it is worse than the one it
replaced: a balance that fails to arrive pushes the requirement *up* (the
child looks empty), but a roster or pool standing that fails to arrive
pushes it *down* — the rows are dropped and `[].every()` still reports
resolved. So a frac registry whose `fetchCommitteePools` errored read as
"fully covered" at a requirement nothing had priced, and the provisional
notice told the operator the number was an over-estimate in exactly the case
where it was not.

`resolved` now covers every input each estimate was built from — periods,
committees, delegations, both rosters, `mbrTopUp`, the frac key length, every
counted committee's pools, and the balances. The reads keep their `data`
possibly-undefined for that reason: an empty roster and an unread one are
indistinguishable once defaulted. `isError` likewise spans every query rather
than the balances alone, and only picks the wording — the gate is `resolved`,
which is false for an absent input however it came to be absent.

The callout no longer claims a direction, since one flag now covers both.

Two more from the same review:

- `countsTowardMbr` used `nowSeconds <= votingEnd`, counting a period as
  fundable for one second after the contracts stop admitting votes
  (`Global.latestTimestamp < votingEnd`, ggovPeriod.algo.ts:408 and
  fracDelegationInstance.algo.ts:962). Now strict, with the check script
  pinning the boundary rather than the off-by-one.
- `poolSignature` keyed only on instance ids, so a staker count that moved
  between refetches left the memo — and the figure — on the previous count.
  It now carries every field `poolRowsOf` keeps.

The estimator already computed a `resolved` flag on every row and every
estimate — "so `required` is final rather than provisional" — and nothing
read it. Three review findings on #117 are three ways of falling through
that gap:

- the top-up button stayed armed while the panel loaded, and an unread
  registry balance falls back to zero spendable, so it offered to send the
  whole requirement;
- an *errored* balance read is not a pending one, so `isLoading` went false
  with the entry simply missing from `byAppId` — the same zero, permanently;
- the frac vote-record key length was absent from the composite loading
  state, and without it the pool list is empty, which makes the frac
  registry read as fully covered at a requirement of zero.

Wire the flag through instead of patching each symptom. `useAppAccountInfos`
now reports `isError` alongside `isLoading`, following the convention
fracQueries.ts already sets for reads whose empty result cannot carry the
difference. `RegistryMbr` gains `resolved` — the registry's own balance plus
every child's, with the frac key length folded in because its absence is
invisible to `[].every()`. The panel shows the figures either way, since an
unread balance can only push a requirement up, but replaces the coverage
callout with a provisional notice and will not offer to fund it.

New `Balances incomplete` story covers the state the panel previously could
not express.