feat: non-blocking warmup — connect during daemon initialization

Instead of blocking the entire UI with "Activating best chain..." until
the daemon finishes warmup, treat warmup responses as a successful
connection. The wallet now:

- Sets connected=true + warming_up=true when daemon returns RPC -28
- Shows warmup status with block progress in the loading overlay
- Polls getinfo every few seconds to detect warmup completion
- Allows Console, Peers, Settings tabs during warmup
- Shows orange status indicator with warmup message in status bar
- Skips balance/tx/address refresh until warmup completes
- Triggers full data refresh once daemon is ready

Also: fix curl handle/header leak on reconnect, fill in empty
externalDetected error branch, bump version to v1.2.0 in build scripts.

scripts/create-appimage.sh

@@ -8,7 +8,7 @@ set -e
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 BUILD_DIR="${SCRIPT_DIR}/build/linux"
 APPDIR="${BUILD_DIR}/AppDir"
-VERSION="1.1.1"
+VERSION="1.2.0"
 
 # Colors
 GREEN='\033[0;32m'

scripts/legacy/build-release.sh

@@ -7,7 +7,7 @@ set -e
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 BUILD_DIR="${SCRIPT_DIR}/build/linux"
-VERSION="1.1.1"
+VERSION="1.2.0"
 
 # Colors for output
 RED='\033[0;31m'