feat(macos): add native menu bar app with notch overlay

Introduces a SwiftUI companion app for the Fail Well PWA: menu bar
status item, popover with task list / record / history views, command
palette, and a Dynamic Island-style notch overlay that shows the active
step and timer beside the hardware notch and expands on hover to reveal
pause/next controls.

macos/Sources/FailWell/Services/StepParser.swift

@@ -0,0 +1,81 @@
+import CryptoKit
+import Foundation
+
+enum StepParser {
+    static func adaptStepsToTextarea(_ steps: [Step]) -> String {
+        steps.map { "- \($0.title) | \($0.estimation)" }.joined(separator: "\n")
+    }
+
+    static func adaptTextareaToSteps(_ value: String) -> [Step] {
+        let lines = value.components(separatedBy: "\n")
+        var result: [(title: String, estimation: Int)] = []
+        var currentParent: (title: String, estimation: Int)?
+        var parentHasChildren = false
+
+        func flushParent() {
+            if let parent = currentParent, !parentHasChildren {
+                result.append(parent)
+            }
+            currentParent = nil
+            parentHasChildren = false
+        }
+
+        for line in lines {
+            let (title, estimation) = extractTitleAndEstimation(from: line)
+            if title.isEmpty { continue }
+
+            if isIndented(line) {
+                if let parent = currentParent, !parent.title.isEmpty {
+                    let flattened = "(\(parent.title)) - \(title)"
+                    result.append((flattened, estimation))
+                    parentHasChildren = true
+                } else {
+                    result.append((title, estimation))
+                }
+            } else {
+                flushParent()
+                currentParent = (title, estimation)
+            }
+        }
+        flushParent()
+
+        // Step identity is derived from title only. Re-estimation must preserve identity so
+        // the existing Step Record (keyed by Step id) survives — see CONTEXT.md §"Re-estimation".
+        let bases = result.map { md5($0.title) }
+        return result.enumerated().map { index, item in
+            let base = bases[index]
+            let duplicates = bases[...index].filter { $0 == base }.count
+            return Step(id: "\(base)-\(duplicates)", title: item.title, estimation: item.estimation)
+        }
+    }
+
+    private static func isIndented(_ line: String) -> Bool {
+        guard let first = line.first else { return false }
+        return first == " " || first == "\t"
+    }
+
+    nonisolated(unsafe) private static let stripPrefix = /^-\s*(\[[ x]\]\s*)?/
+
+    private static func extractTitleAndEstimation(from rawStep: String) -> (String, Int) {
+        let trimmed = rawStep.trimmingCharacters(in: .whitespaces)
+        let stripped = trimmed.replacing(stripPrefix, with: "")
+        let parts = stripped.split(separator: "|", maxSplits: 1, omittingEmptySubsequences: false)
+        let title = parts.first.map { $0.trimmingCharacters(in: .whitespaces) } ?? ""
+        let rawEstimation = parts.count > 1 ? String(parts[1]).trimmingCharacters(in: .whitespaces) : ""
+
+        let estimation: Int
+        if rawEstimation.isEmpty {
+            estimation = 0
+        } else if let d = Double(rawEstimation), !d.isNaN {
+            estimation = Int(d.rounded())
+        } else {
+            estimation = 0
+        }
+        return (title, estimation)
+    }
+
+    private static func md5(_ s: String) -> String {
+        let digest = Insecure.MD5.hash(data: Data(s.utf8))
+        return digest.map { String(format: "%02x", $0) }.joined()
+    }
+}