fix: include anthropic.com cookies in all auth checks and API requests

Claude session cookies are on anthropic.com, not claude.ai. The login
window was not detecting auth (Cancel stayed, no Done) and API calls
were sent without the actual session token.

- claudeCookieHeader: include anthropic.com cookies so the token is
  sent to the usage/bootstrap endpoints
- checkInitialSignInState: detect anthropic.com cookies on startup
- didFinish in LoginView: fire auth when anthropic.com cookies found
- signOut: clear anthropic.com data alongside claude.ai
- notAuthenticated catch: set isSignedIn = false so Settings stays
  in sync with the main panel

ClaudeChecker/UsageViewModel.swift

@@ -43,7 +43,7 @@ class UsageViewModel: ObservableObject {
 
     private func checkInitialSignInState() async {
         let cookies = await WKWebsiteDataStore.default().httpCookieStore.allCookies()
-        let hasAnyCookie = cookies.contains { $0.domain.contains("claude.ai") }
+        let hasAnyCookie = cookies.contains { $0.domain.contains("claude.ai") || $0.domain.contains("anthropic.com") }
         if hasAnyCookie { isSignedIn = true }
     }
 
@@ -51,7 +51,7 @@ class UsageViewModel: ObservableObject {
         let store = WKWebsiteDataStore.default()
         let types = WKWebsiteDataStore.allWebsiteDataTypes()
         let records = await store.dataRecords(ofTypes: types)
-        let claudeRecords = records.filter { $0.displayName.contains("claude.ai") }
+        let claudeRecords = records.filter { $0.displayName.contains("claude.ai") || $0.displayName.contains("anthropic.com") }
         await store.removeData(ofTypes: types, for: claudeRecords)
         UserDefaults.standard.removeObject(forKey: "claude_org_id")
         isSignedIn = false
@@ -109,6 +109,7 @@ class UsageViewModel: ObservableObject {
             checkLimitNotifications(for: limits)
         } catch AppError.notAuthenticated {
             isNotAuthenticated = true
+            isSignedIn = false
             errorMessage = "Not signed in"
         } catch let error as DecodingError {
             switch error {
@@ -192,7 +193,7 @@ class UsageViewModel: ObservableObject {
 
     private func claudeCookieHeader() async -> String? {
         let cookies = await WKWebsiteDataStore.default().httpCookieStore.allCookies()
-        let claudeCookies = cookies.filter { $0.domain.contains("claude.ai") }
+        let claudeCookies = cookies.filter { $0.domain.contains("claude.ai") || $0.domain.contains("anthropic.com") }
         return HTTPCookie.requestHeaderFields(with: claudeCookies)["Cookie"]
     }