Fix Plaid CPQ import quote payloads

Seed Plaid imports with the term shapes the pricing page actually validates, and import percent-priced BPS/Transfer line items as quotePricePercent instead of dropping them on the floor.

1. Why this exists

Plaid's pricing flow is unusual: its product spec renders the subscriptionTerms variable as a free-text input, not as a numeric counter. The pricing engine itself only cares about the numeric input.subscriptionTerms field, but the page-level term validator rejects a quote whose terms[] array contains a {type:'count'} shape where it expects {type:'string'}.

Two consequences fell out of that mismatch on the CPQ import path:

1. Quotes imported from Salesforce CPQ for Plaid landed with a count-typed term and could not be opened on the pricing page without an error.
2. Plaid's Transfer and BPS products price as a percent-of-transaction with optional fee caps — but the import only knew how to build quotePriceFlat, so percent-priced QLIs either got the wrong shape or were silently mishandled.

This PR fixes both: it teaches the seed builder to write the Plaid-shaped term, it adds a small shared helper that keeps the top-level numeric field in sync from either term shape, and it teaches reconstructProductInputs to produce quotePricePercent with floors and ceilings when the source pricing spec is BPS-percent.

2. The two halves of the fix

{
  id: 'subscriptionTerms',
  variableId: 'subscriptionTerms',
  userValue: {
    type: 'count',
    value: 36
  }
}

{
  id: 'subscriptionTerms',
  variableId: 'subscriptionTerms',
  userValue: {
    type: 'string',
    value: '36'
  }
}

{
  type: 'percentWithLimits',
  value: { type: 'percent', value: 0.35 },
  perTxnFloor:   { type: 'currency', value: 0.25, currency: 'USD' },
  perTxnCeiling: { type: 'currency', value: 3,    currency: 'USD' }
}

avgTransactionSize = unitPrice / (rate / 100)
// 0.42 / (0.35 / 100) = 120

3. Code walkthrough

The new helper

apps/server/src/dealops2/services/pricingQuote/subscriptionTerms.ts centralizes parsing. parseSubscriptionTermsValue accepts anything with a value property (or a bare number/string) and returns a positive finite number or undefined:

const parsed =
  typeof raw === 'number'
    ? raw
    : typeof raw === 'string' && raw.trim() !== ''
      ? Number(raw)
      : undefined;

return parsed != null && Number.isFinite(parsed) && parsed > 0
  ? parsed
  : undefined;

syncSubscriptionTermsFromTerm writes the parsed number back to input.subscriptionTerms. normalizeSubscriptionTermsForTextTerm additionally rewrites the term's userValue in place when it's still type:'count'.

The reconstruction split

In reconstructProductInputs.ts, buildProductInputForGroup now returns ProductInput | null so it can opt out of producing a product entirely. Each of the three sub-builders (buildFlatProduct, buildTieredProduct, buildSegmentedProduct) gained the same set of changes:

1. Receive the matched spec so they can read spec.calculationSpec.bpsPercentPricing.
2. Detect percent-priced QLIs via percentRateForQli (which guards against null / NaN).
3. Either return null with an unsupported_bps_percent_shape warning, or build a percent product and pipe it through withAvgTransactionSizeTerm.

The segment collapse check

The "uniform segments collapse to flat" rule is a small predicate:

function canCollapseBpsPercentSegments(qlis) {
  if (qlis.length <= 1) return true;
  const firstRate = percentRateForQli(qlis[0]);
  const firstCap  = qlis[0].Total_Fee_Cap__c ?? null;
  const firstAvg  = deriveAvgTransactionSizeForQli(qlis[0]);
  if (firstRate == null) return false;
  return qlis.every(qli =>
    percentRateForQli(qli) === firstRate &&
    (qli.Total_Fee_Cap__c ?? null) === firstCap &&
    deriveAvgTransactionSizeForQli(qli) === firstAvg);
}

All three of (rate, cap, derived avg txn size) must match across every segment. The PR adds a test for the zero-rate edge case: segments where rate is 0 and cap is null collapse to a flat 0% with MAX_SAFE_INTEGER ceiling, and no avgTransactionSize term is attached because rate <= 0 short-circuits the derivation.

The seed assembler

One-line semantic change in assemblePricingQuoteInput.ts — the seed comment is updated to call out that the term and the top-level numeric field are deliberately different representations of the same value, and the test asserting {type:'count'} is flipped to {type:'string'}.

4. What this doesn't change

5. Risks & open questions