Merge #7244: fix: register shareman recovery interface in ActiveContext

5506d0a fix: register shareman recovery interface in ActiveContext (PastaClaw)

Pull request description:

  ## Summary

  Add missing `shareman->RegisterRecoveryInterface()` call in `ActiveContext::Start()` and corresponding `UnregisterRecoveryInterface()` in `Stop()`.

  ## Problem

  `ActiveContext::Start()` registers recovery interfaces for `cl_signer` and `is_signer` but not `shareman`. Without this, completed sig share sessions are only cleaned up via the 5-second `Cleanup()` interval instead of promptly via `HandleNewRecoveredSig`.

  Under CI load with frozen mocktime, this manifests as flaky test failures in `feature_llmq_signing.py` and `interface_zmq_dash.py` where InstantSend locks don't arrive within expected timeouts.

  ## Root Cause

  The registration was likely dropped during the sig share refactoring that split share management into a separate `shareman` object. The `cl_signer` and `is_signer` registrations survived but `shareman` was missed.

  ## Fix

  Two lines:

  - `shareman->RegisterRecoveryInterface()` in `Start()` (after `is_signer`)
  - `shareman->UnregisterRecoveryInterface()` in `Stop()` (before `is_signer`, maintaining reverse order)

  ## Validation

  - Verified `CSigSharesManager` declares both `RegisterRecoveryInterface()` and `UnregisterRecoveryInterface()` in `src/llmq/signing_shares.h`
  - Confirmed `shareman` is a `unique_ptr<CSigSharesManager>` in `ActiveContext`
  - `Stop()` unregisters in reverse order of `Start()` registration (LIFO)

  Closes #7243

ACKs for top commit:
  UdjinM6:
    utACK 5506d0a
  PastaPastaPasta:
    utACK 5506d0a

Tree-SHA512: e3a6e2e4dd4cddf4447affa6487f596344d855ce957e25013a259eac19a5c8546bb8a2e9be6f356a5f73564f1d1b21789393cadc08d30ca6acc846747debba08

Author: PastaPastaPasta

src/active/context.cpp

@@ -70,6 +70,7 @@ void ActiveContext::Start(CConnman& connman, PeerManager& peerman, int16_t worke
     cl_signer->Start();
     cl_signer->RegisterRecoveryInterface();
     is_signer->RegisterRecoveryInterface();
+    shareman->RegisterRecoveryInterface();
 
     RegisterValidationInterface(cl_signer.get());
 }
@@ -78,6 +79,7 @@ void ActiveContext::Stop()
 {
     UnregisterValidationInterface(cl_signer.get());
 
+    shareman->UnregisterRecoveryInterface();
     is_signer->UnregisterRecoveryInterface();
     cl_signer->UnregisterRecoveryInterface();
     cl_signer->Stop();