v5.3.7: Fix sync stall, transaction display, balance updates, and bootstrap snapshots

Sync fixes:
- Extend stall detection beyond IBD to catch post-IBD sync gaps
- Walk-forward inv continuation to avoid CBlockLocator exponential gap loop
- Track walk-forward progress for stall recovery without restarting from scratch

GUI fixes:
- Load transactions synchronously in constructor (deferred QTimer never fired)
- Use beginResetModel/endResetModel instead of deprecated reset()
- Schedule full refresh on TRY_LOCK failure to avoid dropped CT_NEW notifications
- Only update cachedNumBlocks after successful balance check (prevents permanent loss)
- Add GetAllBalances() single-pass balance retrieval with TRY_LOCK

Bootstrap:
- Add trusted snapshot manifest verification for bootstrap archives
- Add IsKnownCheckpoint() to validate manifest against compiled-in checkpoints
- Skip txleveldb rebuild when verified manifest is present

Bump version to 5.3.7 across all packaging manifests.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packaging/rpm/build-rpm.sh

@@ -4,7 +4,7 @@
 # Install build tools: sudo dnf install rpm-build rpmdevtools
 set -e
 
-VERSION="5.3.6"
+VERSION="5.3.7"
 RELEASE_URL="https://github.com/SamiAhmed7777/triangles_v5/releases/download/v${VERSION}"
 
 echo "Building RPM for Triangles v${VERSION}..."

packaging/rpm/triangles.spec

@@ -1,5 +1,5 @@
 Name:           triangles
-Version:        5.3.6
+Version:        5.3.7
 Release:        1%{?dist}
 Summary:        Cryptographic Triangles (TRI) cryptocurrency wallet
 License:        MIT