fix(runtime-fallback): also classify Volcano Engine errors as quota_exceeded

- Add /exceeded.*quota/i and /usage\s*quota/i to classifyErrorType quota block
- Align /usage.?quota/i -> /usage\s*quota/i in RETRYABLE_ERROR_PATTERNS for consistency
- Strengthen auto-retry-signal test assertion
- Add classifyErrorType assertion to Volcano Engine regression test

Ensures Volcano Engine errors are both retryable AND logged as
errorType: quota_exceeded.

src/hooks/runtime-fallback/auto-retry-signal.test.ts

@@ -15,6 +15,7 @@ describe("extractAutoRetrySignal", () => {
     //#then
     expect(signal).toBeDefined()
     expect(signal?.signal).toContain("exceeded")
+    expect(signal?.signal).toContain("usage quota")
   })
 
   test("detects standard 'quota exceeded' signal", () => {

src/hooks/runtime-fallback/constants.ts

@@ -28,7 +28,7 @@ export const RETRYABLE_ERROR_PATTERNS = [
   /quota\s+will\s+reset\s+after/i,
   /quota.?exceeded/i,
   /exceeded.*quota/i,
-  /usage.?quota/i,
+  /usage\s*quota/i,
   /exhausted\s+your\s+capacity/i,
   /all\s+credentials\s+for\s+model/i,
   /cool(?:ing)?\s+down/i,

src/hooks/runtime-fallback/error-classifier.ts

@@ -126,6 +126,8 @@ export function classifyErrorType(error: unknown): string | undefined {
     errorName?.includes("insufficientquota") ||
     errorName?.includes("billingerror") ||
     /quota.?exceeded/i.test(message) ||
+    /exceeded.*quota/i.test(message) ||
+    /usage\s*quota/i.test(message) ||
     /subscription.*quota/i.test(message) ||
     /insufficient.?(?:quota|balance|funds?)/i.test(message) ||
     /billing.?(?:hard.?)?limit/i.test(message) ||

src/hooks/runtime-fallback/quota-error-classifier.regression.test.ts

@@ -57,7 +57,7 @@ describe("runtime-fallback quota error regressions", () => {
     expect(retryable).toBe(true)
   })
 
-  test("classifies Volcano Engine 'exceeded the usage quota' as retryable", () => {
+  test("classifies Volcano Engine 'exceeded the usage quota' as quota_exceeded and retryable", () => {
     //#given
     const error = {
       name: "SessionRetry",
@@ -65,9 +65,11 @@ describe("runtime-fallback quota error regressions", () => {
     }
 
     //#when
+    const errorType = classifyErrorType(error)
     const retryable = isRetryableError(error, [429, 500, 502, 503, 504])
 
     //#then
+    expect(errorType).toBe("quota_exceeded")
     // Volcano Engine quota errors trigger fallback to the next model
     expect(retryable).toBe(true)
   })