feat(06-02): move processors and platforms to kb_workflow.pipeline

- Move all processor implementations (parse, download, asr, analyze, archive)
- Move all platform adapters (base, bilibili, zhihu)
- Update all internal imports to use kb_workflow.pipeline prefix

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

kb_workflow/pipeline/processors/base.py

@@ -0,0 +1,55 @@
+"""BaseProcessor - Abstract base class for all pipeline processors
+
+Provides a unified interface that all processors (parse, download, asr, analyze)
+must follow, enabling consistent state management and error handling.
+"""
+
+from __future__ import annotations
+
+from abc import ABC, abstractmethod
+from typing import Optional, TYPE_CHECKING
+
+from kb_workflow.pipeline.config import get_settings
+from kb_workflow.pipeline.schemas import StepInput, StepOutput
+
+if TYPE_CHECKING:
+    from kb_workflow.pipeline.state import WorkflowStateManager
+
+
+class BaseProcessor(ABC):
+    """Abstract base class for all pipeline processors.
+
+    All processors (ParseProcessor, DownloadProcessor, ASRProcessor, AnalyzeProcessor)
+    must inherit from this class and implement the process() method.
+
+    Attributes:
+        STEP_NAME: Class attribute identifying the processor step name.
+        settings: KBSettings instance from get_settings().
+        state_manager: Optional WorkflowStateManager for state recording.
+    """
+
+    STEP_NAME: str
+
+    def __init__(self, state_manager: Optional[WorkflowStateManager] = None):
+        """Initialize the processor.
+
+        Args:
+            state_manager: Optional WorkflowStateManager for recording step state.
+        """
+        self.settings = get_settings()
+        self.state_manager = state_manager
+
+    @abstractmethod
+    async def process(self, input_data: StepInput) -> StepOutput:
+        """Process the input data and return the result.
+
+        Args:
+            input_data: Input data for the processor step.
+
+        Returns:
+            StepOutput with processing results.
+
+        Raises:
+            Exception: If processing fails.
+        """
+        pass