feat(06-02): move pipeline core files to kb_workflow.pipeline

- Move pipeline.py, schemas.py, config.py, state.py, errors.py
- Move retry.py, idempotency.py, link_parser.py
- Create pipeline/__init__.py with updated imports
- Update all internal imports to use kb_workflow.pipeline prefix

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

kb_workflow/pipeline/config.py

@@ -0,0 +1,72 @@
+"""Configuration management for KB Pipeline
+
+Provides centralized configuration using pydantic-settings.
+Configuration is loaded from ~/.kb_env file and environment variables.
+"""
+
+from functools import lru_cache
+from pathlib import Path
+from typing import Optional
+
+from pydantic import Field, SecretStr
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class KBSettings(BaseSettings):
+    """KB 工作流配置
+
+    使用 pydantic-settings 从环境变量和 ~/.kb_env 文件加载配置。
+
+    Attributes:
+        base_path: 知识库根目录（必需）
+        archive_path: 归档目录（必需）
+        git_root: Git 仓库根目录（可选）
+        git_user: Git 用户名（可选）
+        git_email: Git 邮箱（可选）
+        hf_token: HuggingFace Token（敏感信息）
+        zhihu_cookie: 知乎 Cookie（敏感信息）
+    """
+
+    model_config = SettingsConfigDict(
+        env_file=str(Path.home() / ".kb_env"),
+        env_file_encoding="utf-8",
+        env_prefix="KB_",
+        extra="ignore",
+    )
+
+    # 必需配置
+    base_path: str = Field(..., description="知识库根目录")
+    archive_path: str = Field(..., description="归档目录")
+    intermediate_path: str = Field(
+        default_factory=lambda: str(Path.home() / "work" / "intermediate" / "analysis"),
+        description="中间文件存储目录"
+    )
+
+    # 可选配置
+    git_root: str = Field(default="", description="Git 仓库根目录")
+    git_user: str = Field(default="", description="Git 用户名")
+    git_email: str = Field(default="", description="Git 邮箱")
+
+    # 敏感信息（从环境变量读取）
+    hf_token: SecretStr = Field(
+        default=SecretStr(""), description="HuggingFace Token"
+    )
+    zhihu_cookie: SecretStr = Field(
+        default=SecretStr(""), description="知乎 Cookie"
+    )
+    bilibili_cookie: SecretStr = Field(
+        default=SecretStr(""), description="B站 Cookie (for video download)"
+    )
+
+
+@lru_cache
+def get_settings() -> KBSettings:
+    """获取配置单例
+
+    使用 lru_cache 确保配置只加载一次。
+    如需重新加载配置，调用 get_settings.cache_clear()。
+
+    Returns:
+        KBSettings 实例
+    """
+    return KBSettings()