fix(api): avoid dify-agent path lookup during Docker build

[BeautyyuYanli]

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Summary

• Fixes API Docker build fails when resolving dev-only dify-agent path #36186.
• Moves dify-agent from API production dependencies to the dev dependency group because it is not currently used by the API runtime.
• Uses uv sync --frozen --no-dev for the API Docker dependency layer so the image build trusts the checked-in lockfile while excluding dev-only path sources outside the api/ build context.
• Follow-up to the Docker build failure reported at feat(agent): init agent server #36087 (comment).

Screenshots

N/A. This is a Docker build/dependency fix.

Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran make lint && make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods

Verification

• uv lock --project api --check
• docker build --target packages -t dify-api-packages:test ./api

This PR is drafted by gpt-5.5(high) and I'm responsible for all the changes. I have reviewed the code and varified the behavior, while breaks may still exist. Reach me to fix in this case.

From gpt-5.5(high)

[dosubot]

Related Knowledge

1 document with suggested updates is ready for review.

dify

Dify Agent Server 模块分析 (Commit 55f95dbc)

View Suggested Changes

@@ -55,7 +55,7 @@
 
 `dify-agent` 包并不替换上述现有组件，而是在其旁边建立了一个**独立的微服务边界**：
 
-- **集成方式**：`api/pyproject.toml` 已将 `dify-agent` 注册为本地路径依赖 [[10]](https://github.com/langgenius/dify/blob/7210f856c9c07ae03d7c2e5def96c949efee6397/api/pyproject.toml)，表明主 API 服务可以作为客户端调用 Agent 服务器
+- **集成方式**：虽然代码结构上 `api/` 可作为客户端调用 Agent 服务器，但 `dify-agent` 目前仅包含在 `api/pyproject.toml` 的 dev 依赖组中 [[10]](https://github.com/langgenius/dify/blob/7210f856c9c07ae03d7c2e5def96c949efee6397/api/pyproject.toml)。API 的生产运行时不使用 dify-agent，生产 Docker 镜像使用 `uv sync --frozen --no-dev` 构建，不包含该包
 - **与 Plugin Daemon 的关系**：新模块直接与 Plugin Daemon（端口 5002）通信，复用了同一个 LLM 提供者运行时基础设施
 - **与 Redis 的关系**：Redis 仅作为持久化存储使用（非作业队列），保存 run 记录和 Redis Stream 事件，两端均可独立扩展
 
@@ -64,7 +64,7 @@
 │                  Dify API (api/)                    │
 │  ┌──────────────┐   ┌──────────────────────────┐   │
 │  │ 旧版 Runner  │   │  dify-agent Client       │   │
-│  │ (CoT / FC)  │   │  (HTTP → Agent Server)   │   │
+│  │ (CoT / FC)  │   │  (开发环境专用)           │   │
 │  └──────┬───────┘   └──────────┬───────────────┘   │
 └─────────┼─────────────────────┼─────────────────────┘
           │                     │
@@ -78,6 +78,8 @@
                             │  Redis   │
                             └──────────┘
 ```
+
+> **注意**：`dify-agent` 目前仅在开发环境中作为 API 的依赖，生产 Docker 构建（`uv sync --frozen --no-dev`）不包含该包。
 
 这一设计标志着 Dify 从**单体同步执行模型**向**异步微服务化 Agent 执行**的架构演进。
 
@@ -1032,7 +1034,7 @@
 新模块与旧版 `BaseAgentRunner` / `CotAgentRunner` / `FunctionCallAgentRunner` 体系**并存而非替代**：
 
 - 旧版 runner 仍承担现有会话式 Agent 的同步执行
-- `dify-agent` 服务器提供了面向微服务架构的新执行路径，主 `api/` 服务通过本地包依赖 [[10]](https://github.com/langgenius/dify/blob/7210f856c9c07ae03d7c2e5def96c949efee6397/api/pyproject.toml) 将其作为客户端调用
+- `dify-agent` 服务器提供了面向微服务架构的新执行路径。虽然代码结构上支持 `api/` 服务作为客户端调用，但 `dify-agent` 目前仅在开发环境中作为依赖，不包含在生产 Docker 镜像中
 - 两者共用同一个 Plugin Daemon 基础设施（端口 5002），无需重复部署
 
 ### 架构演进的意义

[Accept] [Edit] [Decline]

^{How did I do? Any feedback?}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.94%. Comparing base (0d500e6) to head (fe50894).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #36187   +/-   ##
=======================================
  Coverage   85.94%   85.94%           
=======================================
  Files        4454     4454           
  Lines      210903   210903           
  Branches    39426    39426           
=======================================
+ Hits       181254   181257    +3     
+ Misses      26446    26445    -1     
+ Partials     3203     3201    -2     

Flag	Coverage Δ
api	85.42% <ø> (+<0.01%)	⬆️

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[BeautyyuYanli]

cc @asukaminato0721

[BeautyyuYanli]

cc @laipz8200