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/MirrorConfig.swift

@@ -0,0 +1,23 @@
+import Foundation
+import EventKit
+
+struct MirrorConfig {
+    let daysBack: Int
+    let daysForward: Int
+    let mergeGapMin: Int
+    let hideDetails: Bool
+    let copyDescription: Bool
+    let markPrivate: Bool
+    let mirrorAllDay: Bool
+    let overlapMode: OverlapMode
+    let titlePrefix: String
+    let placeholderTitle: String
+    let filterByWorkHours: Bool
+    let workHoursStart: Int
+    let workHoursEnd: Int
+    let excludedTitleFilterTerms: [String]
+    let excludedOrganizerFilterTerms: [String]
+    let mirrorAcceptedOnly: Bool
+    let autoDeleteMissing: Bool
+    let writeEnabled: Bool
+}