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

ROADMAP.md

@@ -11,6 +11,7 @@
 - 1.3.4: persistent file logging, stale-calendar pruning on refresh, clickable top-bar mode toggle
 - 1.3.6: in-app scheduling via `launchd` with hourly/daily/weekday modes
 - 1.3.6: generated macOS app icon set and packaged release assets
+- 1.4.0: unit-test suite (45 tests), Cancel button, progress indicator, sandbox LaunchAgent fix, mirror URL fix, engine refactor into `MirrorConfig`
 
 ## Next
 - Auto-refresh calendars on `EKEventStoreChanged` (live refresh button-less)