Check Chargebee subscriptions against Rillet contracts

**Objective:** For Chargebee customer `{chargebee-customer-id}`, compare Chargebee subscriptions with Rillet contracts and report subscriptions without a contract, contracts without a subscription, and status or date disagreements.

**Step 1: Chargebee subscriptions (chargebee server)**

Call `chargebee-get-customer` with `id` = {chargebee-customer-id} for `email` and `company`. Call `chargebee-get-subscription` with `customer-id` = {chargebee-customer-id}. Keep `id`, `status`, `start-date`, `current-term-end`, `cancelled-at`, `mrr`, `billing-period-unit`, `currency-code`.

**Step 2: Rillet contracts (rillet server)**

Call `rillet-get-customer-emails` and match `email` (fall back to `rillet-get-customers` name match on `company`) to get the Rillet `customer-id`. Call `rillet-get-contracts` with `customer-id` set to it. Keep `contract-id`, `name`, `status`, `start-date`, `end-date`, `total-value`, `currency`. For line detail call `rillet-get-contract-items` with the same `customer-id` (`item-status`, `item-start-date`, `item-end-date`, `price`, `quantity`).

**Step 3: Compare**

Pair each subscription with a contract by closest start date, matching currency, and the Chargebee subscription `id` appearing in the contract `name` if present. Compare: active versus active contract, cancelled versus ended contract, start date, and end date against `current-term-end` or `cancelled-at`. Compare annualised `mrr` times 12 to the contract annual value only if the term is clearly 12 months.

**Step 4: Report**

A table of pairs with the disagreement for each, then separate lists of subscriptions with no contract and contracts with no subscription. Suggest, in words only, what to fix and on which side.

**Rules & Guidelines:**

* `chargebee-get-customer` and `chargebee-get-subscription` are on the chargebee server. `rillet-get-customer-emails`, `rillet-get-customers`, `rillet-get-contracts` and `rillet-get-contract-items` are on the rillet server.
* Read-only. Do not call any Rillet write tool.

**Validation:**

* If the customer is not in Rillet, say so and stop.
* If a pairing is a guess, label it as a guess.
* Do not report value differences across different currencies.