feat: display official subscription quota on Claude provider cards

Read Claude OAuth credentials from macOS Keychain (with file fallback)
and query the Anthropic usage API to show quota utilization inline on
official provider cards. Includes compact countdown timer for reset
windows and hides the rarely-used seven_day_sonnet tier in inline mode.

src/types/subscription.ts

@@ -0,0 +1,30 @@
+export type CredentialStatus =
+  | "valid"
+  | "expired"
+  | "not_found"
+  | "parse_error";
+
+export interface QuotaTier {
+  name: string;
+  utilization: number; // 0-100
+  resetsAt: string | null;
+}
+
+export interface ExtraUsage {
+  isEnabled: boolean;
+  monthlyLimit: number | null;
+  usedCredits: number | null;
+  utilization: number | null;
+  currency: string | null;
+}
+
+export interface SubscriptionQuota {
+  tool: string;
+  credentialStatus: CredentialStatus;
+  credentialMessage: string | null;
+  success: boolean;
+  tiers: QuotaTier[];
+  extraUsage: ExtraUsage | null;
+  error: string | null;
+  queriedAt: number | null;
+}