Fixture/langfuse record auto mode data error (#308)

* fix: 修复状态栏 context 计数器在 loading 时闪现为 0 的问题

第三方 API（如智谱）在 message_start 中可能不返回完整 usage 数据，
导致 getCurrentUsage 返回全零 usage 对象，使 ctx 显示为 0%。

双重保护：
- getCurrentUsage: 跳过全零 usage，继续往前找有真实数据的 message
- calculateContextPercentages: totalInputTokens 为 0 时返回 null

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: 外部化 ESM 包使用 createRequire 替代裸 require

color-diff-napi、image-processor-napi、audio-capture-napi 声明
"type": "module" 但使用裸 require()，Node.js ESM 中 require
不可用。改用 createRequire(import.meta.url) 或顶层 import。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: getDefaultSonnetModel 优先使用用户配置的模型，修复第三方 provider 模型不存在错误

当用户通过 ANTHROPIC_MODEL 或 settings 配置了自定义 provider 支持的模型时，
getDefaultSonnetModel/Haiku/Opus 现在会优先使用该配置，而非硬编码 Anthropic 官方模型 ID。
同时改进 Langfuse 可观测性：sideQuery 失败时记录错误信息到 span，
optional 模式下标记 WARNING 而非 ERROR。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: 将 auto_mode classifier 的 side-query span 绑定到父 trace

classifyYoloAction 及 classifyYoloActionXml 接收 parentSpan 参数，
透传给 sideQuery 调用，使 auto_mode 的 side-query span 嵌套在主 agent trace 下。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: 穷鬼模式下跳过 memdir_relevance side-query

Poor mode 启用时不执行 findRelevantMemories 的预取调用，
避免额外的 API token 消耗。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* chore: 添加 test:all 脚本用于完成任务后的全量检查

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: Vite 构建补齐缺失的 feature flags，修复 auto mode 不可见

Vite 构建插件的 DEFAULT_BUILD_FEATURES 缺少 BUDDY、TRANSCRIPT_CLASSIFIER、
BRIDGE_MODE、ACP、BG_SESSIONS、TEMPLATES，导致 feature('TRANSCRIPT_CLASSIFIER')
被替换为 false，auto mode 从 Shift+Tab 循环中消失。与 build.ts 对齐。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: 统一 feature flags 到 defines.ts，修复 Vite 构建缺失 auto mode

将 DEFAULT_BUILD_FEATURES 列表从 build.ts、dev.ts、vite-plugin-feature-flags.ts
三处内联定义统一到 scripts/defines.ts 单一导出。之前的 Vite 插件缺少
TRANSCRIPT_CLASSIFIER 等 feature flag，导致 auto mode 在 Vite 构建中不可见。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/services/langfuse/index.ts

@@ -1,4 +1,4 @@
 export { initLangfuse, shutdownLangfuse, isLangfuseEnabled, getLangfuseProcessor } from './client.js'
-export { createTrace, createSubagentTrace, recordLLMObservation, recordToolObservation, endTrace, createToolBatchSpan, endToolBatchSpan } from './tracing.js'
+export { createTrace, createSubagentTrace, createChildSpan, recordLLMObservation, recordToolObservation, endTrace, createToolBatchSpan, endToolBatchSpan } from './tracing.js'
 export type { LangfuseSpan } from './tracing.js'
 export { sanitizeToolInput, sanitizeToolOutput, sanitizeGlobal } from './sanitize.js'

src/services/langfuse/tracing.ts

@@ -282,6 +282,60 @@ export function createSubagentTrace(params: {
   }
 }
 
+/**
+ * Create a child span under a parent trace — used for side queries
+ * that should be nested under the main agent trace in Langfuse.
+ */
+export function createChildSpan(
+  parentSpan: LangfuseSpan | null,
+  params: {
+    name: string
+    sessionId: string
+    model: string
+    provider: string
+    input?: unknown
+    querySource?: string
+    username?: string
+  },
+): LangfuseSpan | null {
+  if (!parentSpan || !isLangfuseEnabled()) return null
+  try {
+    const span = startObservation(
+      params.name,
+      {
+        input: params.input,
+        metadata: {
+          provider: params.provider,
+          model: params.model,
+          querySource: params.querySource,
+        },
+      },
+      {
+        asType: 'span',
+        parentSpanContext: parentSpan.otelSpan.spanContext(),
+      },
+    ) as LangfuseSpan
+
+    // Propagate session ID and user ID from parent
+    const parent = parentSpan as unknown as RootTrace
+    const sessionId = parent._sessionId ?? params.sessionId
+    if (sessionId) {
+      span.otelSpan.setAttribute(LangfuseOtelSpanAttributes.TRACE_SESSION_ID, sessionId)
+      ;(span as unknown as RootTrace)._sessionId = sessionId
+    }
+    const userId = parent._userId ?? resolveLangfuseUserId(params.username)
+    if (userId) {
+      span.otelSpan.setAttribute(LangfuseOtelSpanAttributes.TRACE_USER_ID, userId)
+      ;(span as unknown as RootTrace)._userId = userId
+    }
+    logForDebugging(`[langfuse] Child span created: ${span.id} (parent=${parentSpan.id})`)
+    return span
+  } catch (e) {
+    logForDebugging(`[langfuse] createChildSpan failed: ${e}`, { level: 'error' })
+    return null
+  }
+}
+
 export function endTrace(
   rootSpan: LangfuseSpan | null,
   output?: unknown,