fix: add widget target, push entitlement, error handling, force-unwrap

Phase 1 — Widget extension target:
- Add TabataGoWidget target to project.yml (app-extension, iOS 26.0)
- Embed in TabataGo, add to scheme build targets

Phase 2 — Push notification capability:
- Add aps-environment: development to TabataGo.entitlements
- Required by iOS 26 for AppIntents-based Live Activity buttons

Phase 3 — Error handling hardening:
- Catch ActivityAuthorizationError specifically with user message
- Truncate generic errors to 200 chars to avoid UI overflow
- Fix force-unwrap at WorkoutLiveActivity.swift:556 (widgetURL)

tabatago-swift/project.yml

@@ -76,6 +76,8 @@ targets:
 
       - target: TabataGoWatch
         embed: true
+      - target: TabataGoWidget
+        embed: true
     settings:
       base:
         PRODUCT_BUNDLE_IDENTIFIER: fr.millianlmx.tabatago
@@ -156,6 +158,31 @@ targets:
         TARGETED_DEVICE_FAMILY: "4"
         WATCHOS_DEPLOYMENT_TARGET: "11.0"
 
+  TabataGoWidget:
+    type: app-extension
+    platform: iOS
+    deploymentTarget: "26.0"
+    sources:
+      - path: TabataGoWidget
+        excludes:
+          - "**/.DS_Store"
+    info:
+      path: TabataGoWidget/Info.plist
+      properties:
+        CFBundleDisplayName: TabataGoWidget
+        CFBundleShortVersionString: "1.0"
+        CFBundleVersion: "2"
+        NSExtension:
+          NSExtensionPointIdentifier: com.apple.widgetkit-extension
+        NSSupportsLiveActivities: true
+        NSSupportsLiveActivitiesFrequentUpdates: true
+    settings:
+      base:
+        PRODUCT_BUNDLE_IDENTIFIER: fr.millianlmx.tabatago.widget
+        IPHONEOS_DEPLOYMENT_TARGET: "26.0"
+        TARGETED_DEVICE_FAMILY: "1"
+        ENABLE_PREVIEWS: YES
+
   TabataGoTests:
     type: bundle.unit-test
     platform: iOS
@@ -185,6 +212,7 @@ schemes:
     build:
       targets:
         TabataGo: all
+        TabataGoWidget: all
     run:
       config: Debug
     archive: