chore: release v1.7.47-alpha

Sync-perf tuning for bitcoin/bitcoin-core/bitcoin-knots/electrumx.

- Drop the --cpus=2 cap on bitcoin/electrumx variants. Script verification
  is parallelizable; the cap halved IBD speed on 4-8 core machines.
- Bump bitcoin --memory 4g→8g so dbcache=4096 has headroom for mempool +
  connection buffers + I/O. 4g was OOM-prone during heavy IBD.
- Bump electrumx --memory 1g→2g + add CACHE_MB=2048 + MAX_SEND=10MB.
- bitcoin-core CLI args gain -dbcache=4096 -par=0 -maxconnections=125.
- bitcoin-knots manifest matched (1024MB pruned / 4096MB full + par=0).

Future v2: host-RAM-aware dbcache scaling.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## v1.7.47-alpha (2026-04-29)
+
+- Bitcoin Knots/Core sync is now significantly faster. The container now uses every available core for script verification (was capped at 2) and has 8GB of memory instead of 4GB so its 4GB UTXO cache has headroom for the mempool and peer connections. Existing nodes pick up the new limits on next install/update; freshly-installed nodes start at full speed.
+- ElectrumX initial indexing is faster too. Its container memory bumped from 1GB to 2GB and its internal cache is now 2GB (default was 1.2GB).
+
 ## v1.7.46-alpha (2026-04-29)
 
 - Health monitor no longer pages "Auto-restart failed" for orphaned containers. After a variant switch (bitcoin-core ↔ bitcoin-knots) the previous variant's container could survive uninstall and the health monitor would try restarting it forever. Now skipped silently with a debug log.