Support hold invoices when receiving via JIT channels

[f3r10]

Fixes #286.

We already had hold invoices (Bolt11ReceiveForHash + claim/fail) and JIT receive (Bolt11ReceiveViaJitChannel / Bolt11ReceiveVariableAmountViaJitChannel), but not both at once. A node with no inbound channel couldn't create a JIT invoice for a known payment hash and decide later whether to claim.

This adds two RPCs that wrap the existing ldk-node methods (already on the pinned rev, no dependency bump):

• Bolt11ReceiveViaJitChannelForHash
• Bolt11ReceiveVariableAmountViaJitChannelForHash

They're separate RPCs, same split as Bolt11Receive / Bolt11ReceiveForHash, rather than an optional payment_hash on the existing JIT requests. The two JIT modes take different fee-limit fields, so one combined message would make illegal combinations representable.

Requests match the existing JIT ones plus payment_hash. Responses are just invoice. The payment is not auto-claimed; use Bolt11ClaimForId / Bolt11FailForId as with other hold invoices. manually_handle_unknown_bolt11_payments was already set.

Also wired through the client, CLI, and MCP, and updated the hodl / JIT docs. PaymentClaimable comments now name all three hold-invoice RPCs.

E2E: an ldk-server node with no channels, configured with the LSP as a liquidity source, creates a JIT hold invoice, gets paid through the LSP, then claims or fails. The existing JIT e2e used a raw ldk-node as the client; these tests use ldk-server in that role via a TestConfigBuilder lsps_client knob.

[ldk-reviews-bot]

I've assigned @benthecarman as a reviewer!
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Once they submit their review, I'll check if a second reviewer would be helpful.