feat(app): add billing status detection with warning banners per account

Detect HTTP 401/402/403/429 responses and surface them as distinct
BillingStatus states (sessionExpired, paymentRequired, forbidden,
rateLimited) with a styled warning banner at the bottom of each
account card. Also adds JetBrains Mono font files, Theme, and
UsageRings source files.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: phucbm

app/ClaudeUsageMonitor-1.0.0.dmg

@@ -1,5 +1,33 @@
 import Foundation
 
+enum BillingStatus: Equatable {
+    case ok
+    case paymentRequired
+    case sessionExpired
+    case forbidden
+    case rateLimited
+
+    var message: String {
+        switch self {
+        case .ok:              return ""
+        case .paymentRequired: return "Payment required — update billing at claude.ai"
+        case .sessionExpired:  return "Session expired — please refresh your cookie"
+        case .forbidden:       return "Access denied — cookie may be invalid or account suspended"
+        case .rateLimited:     return "Rate limited — too many requests, try again later"
+        }
+    }
+
+    var icon: String {
+        switch self {
+        case .ok:              return ""
+        case .paymentRequired: return "creditcard.trianglebadge.exclamationmark"
+        case .sessionExpired:  return "key.slash"
+        case .forbidden:       return "lock.slash"
+        case .rateLimited:     return "clock.badge.exclamationmark"
+        }
+    }
+}
+
 struct Account: Codable, Identifiable {
     var id: String
     var label: String
@@ -21,6 +49,7 @@ struct Account: Codable, Identifiable {
     var weeklySonnetResetsAt: Date?
     var hasWeeklySonnet: Bool = false
     var errorMessage: String?
+    var billingStatus: BillingStatus = .ok
     var hasFetchedData: Bool = false
     var lastUpdated: Date?
 

app/Sources/Account.swift

@@ -172,8 +172,14 @@ class AccountsManager: ObservableObject {
                 guard let idx = self.accounts.firstIndex(where: { $0.id == accountId }) else { return }
                 if error != nil { self.accounts[idx].errorMessage = "Network error"; self.delegate?.refreshMenuBar(); return }
                 guard let http = response as? HTTPURLResponse else { self.accounts[idx].errorMessage = "Invalid response"; return }
-                if http.statusCode == 200, let data { self.parseUsageData(data, accountIndex: idx) }
-                else { self.accounts[idx].errorMessage = "HTTP \(http.statusCode)" }
+                if http.statusCode == 200, let data {
+                    self.accounts[idx].billingStatus = .ok
+                    self.parseUsageData(data, accountIndex: idx)
+                } else {
+                    self.accounts[idx].billingStatus = Self.billingStatus(for: http.statusCode)
+                    self.accounts[idx].errorMessage = self.accounts[idx].billingStatus == .ok
+                        ? "HTTP \(http.statusCode)" : nil
+                }
                 self.delegate?.refreshMenuBar()
             }
         }.resume()
@@ -213,4 +219,14 @@ class AccountsManager: ObservableObject {
         for i in accounts.indices { accounts[i].updatePercentages() }
     }
 
+    private static func billingStatus(for statusCode: Int) -> BillingStatus {
+        switch statusCode {
+        case 401: return .sessionExpired
+        case 402: return .paymentRequired
+        case 403: return .forbidden
+        case 429: return .rateLimited
+        default:  return .ok
+        }
+    }
+
 }