Add tests for CLI command generation and model alias resolution

- Implement `test-cli-command-gen.js` to verify the logic of `buildCliCommand` function.
- Create `test-e2e-model-alias.js` for end-to-end testing of model alias resolution in `ccw cli`.
- Add `test-model-alias.js` to test model alias resolution for different models.
- Introduce `test-model-alias.txt` for prompt testing with model alias.
- Develop `test-update-claude-command.js` to test command generation for `update_module_claude`.
- Create a test file in `test-update-claude/src` for future tests.

.codex/skills/codex-issue-plan-execute/prompts/execution-agent-system.md

@@ -1,32 +0,0 @@
-⚠️ **DEPRECATED** - This file is deprecated as of v2.0 (2025-01-29)
-
-**Use instead**: [`execution-agent.md`](execution-agent.md)
-
-This file has been merged into `execution-agent.md` to consolidate system prompt + user prompt into a single unified source.
-
-**Why the change?**
-- Eliminates duplication between system and user prompts
-- Reduces token usage by 70% in agent initialization
-- Single source of truth for agent instructions
-- Easier to maintain and update
-
-**Migration**:
-```javascript
-// OLD (v1.0)
-spawn_agent({ message: Read('prompts/execution-agent-system.md') });
-
-// NEW (v2.0)
-spawn_agent({ message: Read('prompts/execution-agent.md') });
-```
-
-**Timeline**:
-- v2.0 (2025-01-29): Old files kept for backward compatibility
-- v2.1 (2025-03-31): Old files will be removed
-
----
-
-# Execution Agent System Prompt (Legacy - See execution-agent.md instead)
-
-See [`execution-agent.md`](execution-agent.md) for the current unified prompt.
-
-All content below is now consolidated into the new unified prompt file.