Release 1.4.0

Fixes:
- Sandbox: add LaunchAgent temporary-exception entitlement
- Mirror URL: fix broken buildMirrorURL (URLComponents with ; separator)
- Cleanup: add bounds check to prevent crash on missing source
- State safety: pass MirrorConfig instead of mutating global @State
- KVC: remove misleading do-catch around setValue:forKey:
- Log cap: limit in-memory log to 2000 lines
- CLI: fix race with calendar loading
- launchCtl: separate stdout/stderr pipes

Features:
- Cancel button for long-running mirrors
- Progress indicator for multi-route runs (Route X of Y)
- Target event cache across routes

Code quality:
- Extract BlockMath, MirrorUtils, EventFilters, MirrorConfig
- Add 45 unit tests across 3 test files
- Refactor mergeGapMin to computed property
- Make log editor read-only

Build:
- Bump version to 1.4.0 (build 18)
- Add LSMinimumSystemVersion 15.5

BusyMirror/BusyMirror.entitlements

@@ -8,5 +8,9 @@
 	<true/>
 	<key>com.apple.security.personal-information.calendars</key>
 	<true/>
+	<key>com.apple.security.temporary-exception.files.home-relative-path.read-write</key>
+	<array>
+		<string>Library/LaunchAgents/</string>
+	</array>
 </dict>
 </plist>