A progressive loan cannot be contract-terminated, so ending one early means using a closure command that means something else

## What is missing

Fineract accepts `contractTermination` and `undoContractTermination` on a loan. It is a distinct closure path for progressive, interest-recalculating loans — not the same thing as `close`, `writeoff` or `foreclosure`, all three of which this app already offers. Neither command appears anywhere in `src/app`.

Confirmed against a running `apache/fineract`, using the #268 discriminator:

| Probe | Result |
|---|---|
| `POST /loans/{id}?command=totallyNotACommand` | `error.msg.query.parameter.value.unsupported` — **unrecognised** (control) |
| `POST /loans/{id}?command=contractTermination` | `error.msg.loan.contract.termination.is.only.supported.for.progressive.loan.schedule.type` — **recognised** |
| `POST /loans/{id}?command=undoContractTermination` | `error.msg.loan.is.not.contract.terminated` — **recognised** |

The platform's own error messages give the two conditions the UI needs: termination applies **only to progressive-schedule loans**, and the undo applies only to a loan already terminated. So both should be offered conditionally rather than unconditionally, the way #268 handled undo-last-disbursal.

## What the UI offers today

The Actions menu on a real **progressive** Active loan — 17 entries, none of them contract termination:


> Add Loan Charge · Add Collateral · Assign Loan Officer · Undo Disbursal · Waive Interest · Prepay Loan · Foreclosure · Close · Close as Rescheduled · Write Off · Charge Off · Merchant Issued Refund · Payout Refund · Goodwill Credit · Waive Interest Payment · Re-age Loan · Re-amortise Loan

For contrast, a cumulative loan gets the first 14 — the three progressive-only entries are correctly withheld, which is the existing pattern this work should follow:


## Suggested scope

Two entries on the loan Actions menu, both gated on the loan's schedule type being progressive, and the undo additionally gated on the loan already being contract-terminated. The generated client already has the call shape — `loansService.postLoansLoanId(loanId, request, 'contractTermination')` — which is the same shape `close` and `writeoff` already use, so this is a new form, not a new pattern.

Request body follows `PostLoansLoanIdRequest`: a date plus `dateFormat`/`locale`, and an optional note.

## Why it is worth doing

Without it, an institution ending a progressive contract early has to reach for `close` or `foreclosure` instead. Those are different events with different accounting consequences, so the loan's history ends up recording something that did not happen — and the distinction is exactly why the platform models termination separately.

## Environment

`main` at `7c51d90b`. Probes against `apache/fineract` running locally via `deploy/docker-compose-e2e.yml`; screenshots from loans seeded with the repository's own `e2e/utils/seed-api.ts` helpers.

Start in src/app at the loan Actions menu and follow the existing close and writeoff entries and handlers. Use the generated loansService.postLoansLoanId call shape with the date, dateFormat, locale, and optional note fields. Done means progressive loans show contract termination, while undo is shown only for already contract-terminated loans, and both actions submit successfully.

Written by the indexing model from the issue text.