feat(dev-workflow): 替换 Codex 为 codeagent 并添加 UI 自动检测

主要变更：
- 全量替换 Codex → codeagent skill 引用
- 添加 UI 自动检测机制（Step 2 分析阶段）
- 实现 backend 分流：后端任务用 codex，UI 任务用 gemini
- 修正 agent 名称：develop-doc-generator → dev-plan-generator
- 更新命令格式为实际的 codeagent-wrapper API
- 放宽 UI 判断标准：样式文件 OR 前端组件（覆盖更多场景）

文件变更：
- dev-workflow/commands/dev.md: 更新 6 步工作流定义
- dev-workflow/README.md: 更新文档和示例
- dev-workflow/agents/dev-plan-generator.md: 更新输入参数说明

保持向后兼容：
- 6 步工作流结构不变
- 90% 测试覆盖率要求不变

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

dev-workflow/commands/dev.md

@@ -1,5 +1,5 @@
 ---
-description: Extreme lightweight end-to-end development workflow with requirements clarification, parallel codex execution, and mandatory 90% test coverage
+description: Extreme lightweight end-to-end development workflow with requirements clarification, parallel codeagent execution, and mandatory 90% test coverage
 ---
 
 
@@ -8,7 +8,7 @@ You are the /dev Workflow Orchestrator, an expert development workflow manager s
 **Core Responsibilities**
 - Orchestrate a streamlined 6-step development workflow:
   1. Requirement clarification through targeted questioning
-  2. Technical analysis using Codex
+  2. Technical analysis using codeagent
   3. Development documentation generation
   4. Parallel development execution
   5. Coverage validation (≥90% requirement)
@@ -20,9 +20,9 @@ You are the /dev Workflow Orchestrator, an expert development workflow manager s
   - Focus questions on functional boundaries, inputs/outputs, constraints, testing, and required unit-test coverage levels
   - Iterate 2-3 rounds until clear; rely on judgment; keep questions concise
 
-- **Step 2: Codex Deep Analysis (Plan Mode Style)**
+- **Step 2: codeagent Deep Analysis (Plan Mode Style)**
 
-  Use Codex Skill to perform deep analysis. Codex should operate in "plan mode" style:
+  Use codeagent Skill to perform deep analysis. codeagent should operate in "plan mode" style and must include UI detection:
 
   **When Deep Analysis is Needed** (any condition triggers):
   - Multiple valid approaches exist (e.g., Redis vs in-memory vs file-based caching)
@@ -30,7 +30,11 @@ You are the /dev Workflow Orchestrator, an expert development workflow manager s
   - Large-scale changes touching many files or systems
   - Unclear scope requiring exploration first
 
-  **What Codex Does in Analysis Mode**:
+  **UI Detection Requirements**:
+  - During analysis, output whether the task needs UI work (yes/no) and the evidence
+  - UI criteria: presence of style assets (.css, .scss, styled-components, CSS modules, tailwindcss) OR frontend component files (.tsx, .jsx, .vue)
+
+  **What codeagent Does in Analysis Mode**:
   1. **Explore Codebase**: Use Glob, Grep, Read to understand structure, patterns, architecture
   2. **Identify Existing Patterns**: Find how similar features are implemented, reuse conventions
   3. **Evaluate Options**: When multiple approaches exist, list trade-offs (complexity, performance, security, maintainability)
@@ -53,6 +57,10 @@ You are the /dev Workflow Orchestrator, an expert development workflow manager s
 
   ## Task Breakdown
   [2-5 tasks with: ID, description, file scope, dependencies, test command]
+
+  ## UI Determination
+  needs_ui: [true/false]
+  evidence: [files and reasoning tied to style + component criteria]
   ```
 
   **Skip Deep Analysis When**:
@@ -62,24 +70,37 @@ You are the /dev Workflow Orchestrator, an expert development workflow manager s
 
 - **Step 3: Generate Development Documentation**
   - invoke agent dev-plan-generator
+  - When creating `dev-plan.md`, append a dedicated UI task if Step 2 marked `needs_ui: true`
   - Output a brief summary of dev-plan.md:
     - Number of tasks and their IDs
     - File scope for each task
     - Dependencies between tasks
     - Test commands
   - Use AskUserQuestion to confirm with user:
-    - Question: "Proceed with this development plan?"
+    - Question: "Proceed with this development plan?" (if UI work is detected, state that UI tasks will use the gemini backend)
     - Options: "Confirm and execute" / "Need adjustments"
   - If user chooses "Need adjustments", return to Step 1 or Step 2 based on feedback
 
 - **Step 4: Parallel Development Execution**
-  - For each task in `dev-plan.md`, invoke Codex with this brief:
-    ```
+  - For each task in `dev-plan.md`, invoke codeagent skill with task brief in HEREDOC format:
+    ```bash
+    # Backend task (use codex backend - default)
+    codeagent-wrapper --backend codex - <<'EOF'
     Task: [task-id]
     Reference: @.claude/specs/{feature_name}/dev-plan.md
     Scope: [task file scope]
     Test: [test command]
     Deliverables: code + unit tests + coverage ≥90% + coverage summary
+    EOF
+
+    # UI task (use gemini backend - enforced)
+    codeagent-wrapper --backend gemini - <<'EOF'
+    Task: [task-id]
+    Reference: @.claude/specs/{feature_name}/dev-plan.md
+    Scope: [task file scope]
+    Test: [test command]
+    Deliverables: code + unit tests + coverage ≥90% + coverage summary
+    EOF
     ```
   - Execute independent tasks concurrently; serialize conflicting ones; track coverage reports
 
@@ -92,7 +113,7 @@ You are the /dev Workflow Orchestrator, an expert development workflow manager s
   - Provide completed task list, coverage per task, key file changes
 
 **Error Handling**
-- Codex failure: retry once, then log and continue
+- codeagent failure: retry once, then log and continue
 - Insufficient coverage: request more tests (max 2 rounds)
 - Dependency conflicts: serialize automatically