feat: add widget extension — small, medium, large

- KisaniCalWidget: 3 sizes sharing the app's design language
  Small: date badge + kisaniCAL. wordmark + task count
  Medium: badge + task list (3 items) + workout row
  Large: badge + full task list (6 items) + workout row

- WidgetDataStore (Shared/): lightweight Codable types for App Group
  UserDefaults cross-process data exchange

- WidgetBridge: TaskViewModel/WorkoutViewModel extensions that sync
  data into App Group and call WidgetCenter.reloadAllTimelines()

- ContentView: calls syncWidget() on appear and scene becoming active

- project.yml + entitlements updated; project regenerated via xcodegen

KisaniCalWidget/KisaniCalWidget.entitlements

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <key>com.apple.security.application-groups</key>
+    <array>
+        <string>group.com.kutesir.KisaniCal</string>
+    </array>
+</dict>
+</plist>