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

project.yml

@@ -13,6 +13,7 @@ targets:
     deploymentTarget: "16.0"
     sources:
       - path: KisaniCal
+      - path: Shared
     settings:
       base:
         SWIFT_VERSION: 5.9
@@ -28,5 +29,27 @@ targets:
         ASSETCATALOG_COMPILER_GLOBAL_ACCENT_COLOR_NAME: AccentColor
         CODE_SIGN_STYLE: Automatic
         ENABLE_PREVIEWS: YES
+        CODE_SIGN_ENTITLEMENTS: KisaniCal/KisaniCal.entitlements
         INFOPLIST_KEY_NSCalendarsUsageDescription: "Kisani Cal shows your calendar events alongside tasks."
         INFOPLIST_KEY_NSCalendarsFullAccessUsageDescription: "Kisani Cal shows your calendar events alongside tasks."
+    dependencies:
+      - target: KisaniCalWidget
+        embed: true
+
+  KisaniCalWidget:
+    type: app-extension
+    platform: iOS
+    deploymentTarget: "16.0"
+    sources:
+      - path: KisaniCalWidget
+      - path: Shared
+    settings:
+      base:
+        SWIFT_VERSION: 5.9
+        PRODUCT_BUNDLE_IDENTIFIER: com.kutesir.KisaniCal.widget
+        GENERATE_INFOPLIST_FILE: YES
+        INFOPLIST_KEY_NSExtensionPointIdentifier: com.apple.widgetkit-extension
+        CODE_SIGN_STYLE: Automatic
+        CODE_SIGN_ENTITLEMENTS: KisaniCalWidget/KisaniCalWidget.entitlements
+        SKIP_INSTALL: YES
+        LD_RUNPATH_SEARCH_PATHS: "$(inherited) @executable_path/Frameworks @executable_path/../../Frameworks"