fix(provider-defaults): bump default Anthropic model to claude-sonnet-4-5-20250929

The previous default `claude-sonnet-4-20250514` returns 404 from the Anthropic
API today, breaking every published example that says `provider: 'anthropic'`
without an explicit `model:`. Bump default to `claude-sonnet-4-5-20250929`
(verified working) for both `anthropic` and `claude-code-cli` providers, and
update the matching spec assertion so it doesn't drift.

Author: jddunn

src/api/runtime/provider-defaults.ts

@@ -42,7 +42,7 @@ export const PROVIDER_DEFAULTS: Record<string, ProviderDefaults> = {
     cheap: 'gpt-4o-mini',
   },
   anthropic: {
-    text: 'claude-sonnet-4-20250514',
+    text: 'claude-sonnet-4-5-20250929',
     cheap: 'claude-haiku-4-5-20251001',
   },
   ollama: {
@@ -60,7 +60,7 @@ export const PROVIDER_DEFAULTS: Record<string, ProviderDefaults> = {
     cheap: 'gemini-2.0-flash',
   },
   'claude-code-cli': {
-    text: 'claude-sonnet-4-20250514',
+    text: 'claude-sonnet-4-5-20250929',
     cheap: 'claude-haiku-4-5-20251001',
   },
   'gemini-cli': {

src/core/llm/providers/tests/OpenAICompatProviders.spec.ts

@@ -278,7 +278,7 @@ describe('OpenAI-compatible provider wrappers', () => {
 
     it('still has anthropic defaults', () => {
       expect(PROVIDER_DEFAULTS.anthropic).toBeDefined();
-      expect(PROVIDER_DEFAULTS.anthropic.text).toBe('claude-sonnet-4-20250514');
+      expect(PROVIDER_DEFAULTS.anthropic.text).toBe('claude-sonnet-4-5-20250929');
       expect(PROVIDER_DEFAULTS.anthropic.cheap).toBe('claude-haiku-4-5-20251001');
     });
   });