feat: remove legacy OpenCode runtime

Cut product flows over to Coding/Pi and retain only the migration-owned v1 boundary. Promote supported native optional packages because electron-builder omitted pnpm transitive optional closure from the packaged ASAR.

shared/ai-gateway-error-kind.ts

@@ -0,0 +1,30 @@
+export type AIGatewayErrorKind = 'quota_exhausted' | 'authentication_invalid';
+
+export function isTokenBalanceExhausted(message: string | null | undefined): boolean {
+  const normalized = message?.trim().toLowerCase() ?? '';
+  return normalized.includes('token_balance_exhausted')
+    || normalized.includes('token balance exhausted')
+    || normalized.includes('balance exhausted');
+}
+
+export function getAIGatewayErrorKind(message: string | null | undefined): AIGatewayErrorKind | null {
+  const normalized = message?.trim().toLowerCase() ?? '';
+  if (!normalized) return null;
+  if (
+    isTokenBalanceExhausted(normalized)
+    || normalized.includes('user quota is not enough')
+    || normalized.includes('quota is not enough')
+    || normalized.includes('quota not enough')
+    || normalized.includes('insufficient quota')
+    || normalized.includes('quota exhausted')
+    || normalized.includes('quota exceeded')
+    || normalized.includes('rolling 5-hour window')
+    || normalized.includes('额度不足')
+  ) {
+    return 'quota_exhausted';
+  }
+  if (normalized.includes('works_square_gateway_authorize_failed')) {
+    return 'authentication_invalid';
+  }
+  return null;
+}