fix(oauth+errors): OAuth silent refresh, quota STOP patterns, compaction loop cap

Bug fixes:
1. OAuth token refresh (#3149): buildHttpRequestInit() now attempts silent refresh
   via refresh_token before triggering full browser re-auth. Added refresh() method
   to McpOAuthProvider. Includes test isolation fix for discovery mock.

2. Quota error STOP (#3126): Added STOP_MESSAGE_PATTERNS in model-error-classifier
   that take precedence over RETRYABLE_MESSAGE_PATTERNS. Message-only quota errors
   now non-retryable. Runtime-fallback: quota_exceeded with 'retrying in' signal
   still triggers fallback (provider-managed auto-retry). Restored removed patterns.

3. Compaction loop (#3127): MAX_RECOVERY_ATTEMPTS=3 cap + additional suppression
   guard from opencode session in degradation monitor.

Also: refactored extractAutoRetrySignal to auto-retry-signal.ts, new regression
tests for quota classifier and compaction degradation monitor.

src/hooks/runtime-fallback/constants.ts

@@ -11,7 +11,7 @@ import type { RuntimeFallbackConfig } from "../../config"
  */
 export const DEFAULT_CONFIG: Required<RuntimeFallbackConfig> = {
   enabled: false,
-  retry_on_errors: [402, 429, 500, 502, 503, 504],
+  retry_on_errors: [429, 500, 502, 503, 504],
   max_fallback_attempts: 3,
   cooldown_seconds: 60,
   timeout_seconds: 30,
@@ -25,26 +25,21 @@ export const DEFAULT_CONFIG: Required<RuntimeFallbackConfig> = {
 export const RETRYABLE_ERROR_PATTERNS = [
   /rate.?limit/i,
   /too.?many.?requests/i,
-  /quota.?exceeded/i,
   /quota\s+will\s+reset\s+after/i,
+  /quota.?exceeded/i,
   /(?:you(?:'ve|\s+have)\s+)?reached\s+your\s+usage\s+limit/i,
-  /all\s+credentials\s+for\s+model/i,
-  /cool(?:ing)?\s+down/i,
   /exhausted\s+your\s+capacity/i,
   /usage\s+limit\s+has\s+been\s+reached/i,
+  /all\s+credentials\s+for\s+model/i,
+  /cool(?:ing)?\s+down/i,
   /model.{0,20}?not.{0,10}?supported/i,
   /model_not_supported/i,
+  /insufficient.?(?:credits?|funds?|balance)/i,
+  /credit.*balance.*too.*low/i,
   /service.?unavailable/i,
   /overloaded/i,
   /temporarily.?unavailable/i,
   /try.?again/i,
-  /credit.*balance.*too.*low/i,
-  /insufficient.?(?:credits?|funds?|balance)/i,
-  /subscription.*quota/i,
-  /billing.?(?:hard.?)?limit/i,
-  /payment.?required/i,
-  /out\s+of\s+credits?/i,
-  /(?:^|\s)402(?:\s|$)/,
   /(?:^|\s)429(?:\s|$)/,
   /(?:^|\s)503(?:\s|$)/,
   /(?:^|\s)529(?:\s|$)/,