fix: replace hardcoded ~/.desirecore paths with ${DESIRECORE_ROOT} variable (#16)

## Summary

- 将所有技能文件中的硬编码 `~/.desirecore/` 和 `$HOME/.desirecore/` 路径替换为
`${DESIRECORE_ROOT}/` 变量
- 递增 manifest.json version 至 1.2.1

## Why

dev 模式下 `DESIRECORE_HOME=~/.desirecore-dev`，硬编码路径导致技能读取错误的端口文件和目录。主仓库的
`variable-substitutor.ts` 会在运行时将 `${DESIRECORE_ROOT}` 替换为实际根目录。

## Test plan

- [ ] `npm run dev` 启动后触发任意技能，确认端口路径解析为
`~/.desirecore-dev/agent-service.port`
- [ ] prod 模式确认路径为 `~/.desirecore/agent-service.port`

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

skills/update-agent/SKILL.md

@@ -36,7 +36,7 @@ metadata:
         Safely update an existing Agent's config, persona, principles, skills, and memory, producing reviewable diffs that are applied and committed only after confirmation. Use when the user asks to modify Agent behavior, install/uninstall skills, adjust config, roll back changes, or revise rules.
       body: ./SKILL.md
       source_hash: sha256:a0fecd84f92204bd
-      translated_by: ai:claude-opus-4-7
+      translated_by: human
       translated_at: '2026-05-03'
 market:
   icon: >-
@@ -200,7 +200,7 @@ diff_metadata:
 
 Apply the change by reading and writing files directly through AgentFS. **Do not call HTTP APIs, and do not operate Git directly** (version management is handled automatically by the backend).
 
-**AgentFS root directory**: `~/.desirecore/agents/<agentId>/`
+**AgentFS root directory**: `${DESIRECORE_ROOT}/agents/<agentId>/`
 
 **Read file**: Use the `cat` command to read the current contents of the target file.
 
@@ -231,7 +231,7 @@ After a successful change, present a user-friendly receipt (do not expose intern
 
 ```bash
 # 查看版本历史
-cd ~/.desirecore/agents/<agentId>
+cd ${DESIRECORE_ROOT}/agents/<agentId>
 git log --oneline -10
 
 # 查看某个版本的文件内容
@@ -246,12 +246,12 @@ git show <commit>:persona.md
 
 | User Intent                  | Target File     | AgentFS Path                                   |
 | ---------------------------- | --------------- | ---------------------------------------------- |
-| Modify personality/style     | `persona.md`    | `~/.desirecore/agents/<agentId>/persona.md`    |
-| Modify behavioral rules      | `principles.md` | `~/.desirecore/agents/<agentId>/principles.md` |
-| Install/uninstall skills     | `skills/`       | `~/.desirecore/agents/<agentId>/skills/`       |
-| Modify tools config          | `tools/`        | `~/.desirecore/agents/<agentId>/tools/`        |
-| Add memory                   | `memory/`       | `~/.desirecore/agents/<agentId>/memory/`       |
-| Modify runtime config        | `agent.json`    | `~/.desirecore/agents/<agentId>/agent.json`    |
+| Modify personality/style     | `persona.md`    | `${DESIRECORE_ROOT}/agents/<agentId>/persona.md`    |
+| Modify behavioral rules      | `principles.md` | `${DESIRECORE_ROOT}/agents/<agentId>/principles.md` |
+| Install/uninstall skills     | `skills/`       | `${DESIRECORE_ROOT}/agents/<agentId>/skills/`       |
+| Modify tools config          | `tools/`        | `${DESIRECORE_ROOT}/agents/<agentId>/tools/`        |
+| Add memory                   | `memory/`       | `${DESIRECORE_ROOT}/agents/<agentId>/memory/`       |
+| Modify runtime config        | `agent.json`    | `${DESIRECORE_ROOT}/agents/<agentId>/agent.json`    |
 
 ### Error Handling
 
@@ -285,7 +285,7 @@ git show <commit>:persona.md
 
 ```bash
 # 1. 读取当前 persona.md
-cat ~/.desirecore/agents/legal-assistant/persona.md
+cat ${DESIRECORE_ROOT}/agents/legal-assistant/persona.md
 
 # 输出示例:
 # # 法律顾问小助手
@@ -304,7 +304,7 @@ cat ~/.desirecore/agents/legal-assistant/persona.md
 # 3. 用户确认后，直接编辑文件，将 Personality 和 Communication Style 修改为目标值
 
 # 4. 验证写入结果
-cat ~/.desirecore/agents/legal-assistant/persona.md
+cat ${DESIRECORE_ROOT}/agents/legal-assistant/persona.md
 ```
 
 ---