docs: clarify brainstorm vs plan workflow and add decision guide

Major improvements to workflow understanding and guidance:

1. New Document: WORKFLOW_DECISION_GUIDE.md
   - Comprehensive decision flowchart for full software lifecycle
   - Interactive Mermaid diagram with 40+ decision points
   - Clear guidance on when to use each command
   - Real-world scenarios for all workflow types
   - Quick reference tables by knowledge level, project stage, and mode
   - Expert tips and common pitfalls

2. Clarified Brainstorm vs Plan Relationship
   Core concept correction:
   - Brainstorm: Use when you know WHAT to build, NOT HOW
   - Plan: Use when you know both WHAT and HOW
   - Plan can accept user input OR brainstorm output

3. Updated Documentation Files
   - GETTING_STARTED.md: Added clear distinction and decision criteria
   - GETTING_STARTED_CN.md: Chinese version with same clarifications
   - FAQ.md: Enhanced brainstorm usage explanation with workflow comparison table
   - README.md: Added Workflow Decision Guide link
   - README_CN.md: Added Chinese link to decision guide

4. Key Improvements
   When to Use Brainstorming:
   - Unclear solution approach (multiple ways to solve)
   - Architectural exploration needed
   - Requirements clarification (high-level clear, details not)
   - Multiple trade-offs to analyze
   - Unfamiliar domain

   When to Skip Brainstorming:
   - Clear implementation approach
   - Similar to existing code patterns
   - Well-defined requirements
   - Simple features

5. Decision Flowchart Covers:
   - Ideation phase (know what to build?)
   - Design phase (know how to build?)
   - UI design phase (need UI design?)
   - Planning phase (complexity level?)
   - Testing phase (TDD, post-test, test-fix?)
   - Review phase (security, architecture, quality?)
   - Completion

Benefits:
- Eliminates confusion about brainstorm usage
- Provides clear decision criteria for all commands
- Visual flowchart helps users navigate workflows
- Comprehensive coverage of all development stages
- Reduces trial-and-error in workflow selection

Files modified: 5
Files added: 1 (WORKFLOW_DECISION_GUIDE.md)

FAQ.md

@@ -164,14 +164,31 @@ That's it! CCW handles planning, task generation, and implementation.
 
 ### When should I use brainstorming workflows?
 
-Use `/workflow:brainstorm:auto-parallel` when:
-- Feature requires multiple perspectives (architecture, security, UX, etc.)
-- You need thorough requirements analysis
-- Architecture decisions have significant impact
-- Starting a complex project from scratch
+**Use `/workflow:brainstorm:auto-parallel` when you know WHAT to build, but NOT HOW to build it.**
+
+**Brainstorming scenarios**:
+- 🤔 **Unclear solution approach** - Multiple ways to solve the problem, need expert analysis
+- 🏗️ **Architectural exploration** - Need to explore different architectural patterns
+- 📋 **Requirements clarification** - High-level goal is clear, but technical details are not
+- 🔀 **Multiple trade-offs** - Need to analyze pros/cons of different approaches
+- 🆕 **Unfamiliar domain** - Building something new without clear implementation path
+
+**Skip brainstorming, use `/workflow:plan` directly when**:
+- ✅ **Clear implementation approach** - You already know how to build it
+- ✅ **Similar to existing code** - Following established patterns in your codebase
+- ✅ **Well-defined requirements** - Technical specs are clear from the start
+- ✅ **Simple features** - Straightforward implementation, no architectural decisions
+
+**Workflow comparison**:
+
+| Know what + Know how | Know what, NOT how |
+|---------------------|-------------------|
+| `/workflow:plan "Add JWT auth"` | `/workflow:brainstorm:auto-parallel "Design auth system"` → `/workflow:plan` |
+| Plan generates tasks directly | Brainstorm explores solutions → Plan generates tasks |
 
 **Example**:
 ```bash
+# When you DON'T know how to build it
 /workflow:brainstorm:auto-parallel "Build real-time collaborative document editing system"
 /workflow:plan
 /workflow:execute