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/BlockMath.swift

@@ -0,0 +1,75 @@
+import Foundation
+
+struct Block: Hashable {
+    let start: Date
+    let end: Date
+    let srcStableID: String?  // stable source item ID for reschedule tracking
+    let label: String?        // source title (for dry-run / non-private)
+    let notes: String?        // source notes (for optional copy)
+    let occurrence: Date?     // occurrenceDate for recurring instances
+}
+
+// De-dup blocks by occurrence (preferred) or by time range
+func uniqueBlocks(_ blocks: [Block], trackByID: Bool) -> [Block] {
+    var seen = Set<String>()
+    var out: [Block] = []
+    for b in blocks {
+        let key: String
+        if trackByID, let sid = b.srcStableID {
+            let occ = b.occurrence.map { String($0.timeIntervalSince1970) } ?? "-"
+            key = "id|\(sid)|\(occ)"
+        } else {
+            key = "t|\(b.start.timeIntervalSince1970)|\(b.end.timeIntervalSince1970)"
+        }
+        if seen.insert(key).inserted { out.append(b) }
+    }
+    return out
+}
+
+func mergeBlocks(_ blocks: [Block], gapMinutes: Int) -> [Block] {
+    guard !blocks.isEmpty else { return [] }
+    let sorted = blocks.sorted { $0.start < $1.start }
+    var out: [Block] = []
+    var cur = Block(start: sorted[0].start, end: sorted[0].end, srcStableID: nil, label: nil, notes: nil, occurrence: nil)
+    for b in sorted.dropFirst() {
+        let gap = b.start.timeIntervalSince(cur.end) / 60.0
+        if gap <= Double(gapMinutes) {
+            if b.end > cur.end { cur = Block(start: cur.start, end: b.end, srcStableID: nil, label: nil, notes: nil, occurrence: nil) }
+        } else {
+            out.append(cur)
+            cur = Block(start: b.start, end: b.end, srcStableID: nil, label: nil, notes: nil, occurrence: nil)
+        }
+    }
+    out.append(cur)
+    return out
+}
+
+func coalesce(_ segs: [Block]) -> [Block] { mergeBlocks(segs, gapMinutes: 0) }
+
+func fullyCovered(_ mergedSegs: [Block], block: Block, tolMin: Double) -> Bool {
+    for s in mergedSegs {
+        if s.start <= block.start.addingTimeInterval(tolMin * 60),
+           s.end >= block.end.addingTimeInterval(-tolMin * 60) { return true }
+    }
+    return false
+}
+
+func gapsWithin(_ mergedSegs: [Block], in block: Block) -> [Block] {
+    if mergedSegs.isEmpty { return [Block(start: block.start, end: block.end, srcStableID: nil, label: nil, notes: nil, occurrence: nil)] }
+    var segs: [Block] = []
+    for s in mergedSegs where s.end > block.start && s.start < block.end {
+        let ss = max(s.start, block.start)
+        let ee = min(s.end, block.end)
+        if ee > ss { segs.append(Block(start: ss, end: ee, srcStableID: nil, label: nil, notes: nil, occurrence: nil)) }
+    }
+    if segs.isEmpty { return [Block(start: block.start, end: block.end, srcStableID: nil, label: nil, notes: nil, occurrence: nil)] }
+    let merged = coalesce(segs)
+    var gaps: [Block] = []
+    var prevEnd = block.start
+    for s in merged {
+        if s.start > prevEnd { gaps.append(Block(start: prevEnd, end: s.start, srcStableID: nil, label: nil, notes: nil, occurrence: nil)) }
+        if s.end > prevEnd { prevEnd = s.end }
+    }
+    if prevEnd < block.end { gaps.append(Block(start: prevEnd, end: block.end, srcStableID: nil, label: nil, notes: nil, occurrence: nil)) }
+    return gaps
+}