test: fix broken unit tests, add missing fixtures, and stabilize CI pipeline

- Fix os module mock pattern for Vitest v4 in proxy-ide-config tests

- Fix enterprise oauth_client_key expectations in cloudHandler-sync and token-manager-parity tests

- Fix proxy-controller integration test argument expectations

- Add missing proxy-parity JSON fixtures (OpenAI tools, Anthropic tool-use, Gemini SSE)

- Add reasoning_content mapping to convertClaudeToOpenAIResponse

- Fix google-api service test env var cache leak with resetModules + dynamic imports

- Fix proxy-metrics timer tests by calling onModuleInit in beforeEach

- Fix locale-sensitive number formatting in StatCard tests

- Add missing test files to version control (components, hooks, ipc, mocks, server, utils)

- Fix CI workflows: testing.yaml (use vitest run, add type-check job, npm cache), lint.yaml and format.yaml (add npm cache, concurrency, fix job names)

src/server/modules/proxy/proxy.service.ts

@@ -1906,6 +1906,7 @@ export class ProxyService {
             // When tool_calls are present, content must be null per OpenAI spec.
             content: toolCalls.length > 0 ? null : finalContent || '',
             tool_calls: toolCalls.length > 0 ? toolCalls : undefined,
+            reasoning_content: reasoningContent || undefined,
           },
           finish_reason: this.mapAnthropicStopReasonToOpenAIFinishReason(
             claudeResponse.stop_reason,