feat(knowledge): 任务队列、独立 worker 与 pgvector 向量索引

知识处理改为数据库任务队列，独立 worker 做切块与向量化，失败可重试。

backend/app/workers/run_knowledge_processor.py

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+"""
+Copyright 2024-2026 ChatterMate
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+"""
+Knowledge Processor Runner
+This script runs the knowledge processor independently at regular intervals.
+"""
+
+import asyncio
+import sys
+import os
+from pathlib import Path
+
+# Add the parent directory to Python path to allow imports
+sys.path.append(str(Path(__file__).parent.parent.parent))
+
+from app.workers.knowledge_processor import run_processor
+from app.core.logger import get_logger
+from app.services.firebase import initialize_firebase
+
+logger = get_logger(__name__)
+
+# Configure polling interval
+POLL_INTERVAL = int(os.environ.get('POLL_INTERVAL', '10'))  # Default to 10 seconds
+WORKER_ID = os.environ.get('GUNICORN_WORKER_ID', 'standalone')
+
+# Initialize Firebase on module load
+try:
+    logger.info(f"Initializing Firebase for worker {WORKER_ID}...")
+    initialize_firebase()
+    logger.info(f"Worker {WORKER_ID}: Firebase initialized successfully")
+except Exception as e:
+    logger.error(f"Worker {WORKER_ID}: Failed to initialize Firebase: {e}")
+
+async def run_processor_loop():
+    """Run the knowledge processor in a continuous loop with short poll interval"""
+    logger.info(f"Worker {WORKER_ID}: Starting knowledge processor with {POLL_INTERVAL}s polling interval")
+    
+    try:
+        logger.info(f"Worker {WORKER_ID}: Starting knowledge processor loop")
+        iteration = 0
+        
+        while True:
+            iteration += 1
+            start_time = asyncio.get_event_loop().time()
+            
+            try:
+                logger.info(f"Worker {WORKER_ID}: Iteration {iteration} - Checking for pending knowledge items...")
+                await run_processor()
+                logger.info(f"Worker {WORKER_ID}: Iteration {iteration} - Processing completed successfully")
+            except Exception as e:
+                logger.error(f"Worker {WORKER_ID}: Iteration {iteration} - Error in knowledge processor: {str(e)}")
+
+            # FAQ generation jobs ride the same loop in this entrypoint too, so
+            # both worker entrypoints drain the FAQ queue.
+            try:
+                from app.workers.faq_processor import run_faq_processor
+                await run_faq_processor()
+            except Exception as e:
+                logger.error(f"Worker {WORKER_ID}: Iteration {iteration} - Error in FAQ processor: {str(e)}")
+            
+            # Calculate how long the processing took
+            elapsed = asyncio.get_event_loop().time() - start_time
+            logger.info(f"Worker {WORKER_ID}: Iteration {iteration} - Processing took {elapsed:.2f} seconds")
+            
+            # If the processing took less than the polling interval, sleep for the remainder
+            sleep_time = max(0.1, POLL_INTERVAL - elapsed)
+            logger.info(f"Worker {WORKER_ID}: Iteration {iteration} - Sleeping for {sleep_time:.2f} seconds before next check")
+            await asyncio.sleep(sleep_time)
+            
+    except Exception as e:
+        logger.error(f"Worker {WORKER_ID}: Fatal error in knowledge processor: {str(e)}")
+        sys.exit(1)
+
+def app(environ, start_response):
+    """WSGI application for health checks"""
+    status = '200 OK'
+    headers = [('Content-type', 'application/json')]
+    start_response(status, headers)
+    return [b'{"status": "running"}']
+
+# Set worker ID if running under Gunicorn
+if 'GUNICORN_WORKER_ID' not in os.environ and 'GUNICORN_ARBITER' in os.environ:
+    pid = os.getpid()
+    os.environ['GUNICORN_WORKER_ID'] = f"worker-{pid}"
+    WORKER_ID = f"worker-{pid}"
+
+# Start the processor loop in the background when Gunicorn loads this module
+logger.info(f"Worker {WORKER_ID}: Initializing knowledge processor worker")
+loop = asyncio.new_event_loop()
+asyncio.set_event_loop(loop)
+task = loop.create_task(run_processor_loop())
+
+if __name__ == "__main__":
+    try:
+        asyncio.run(run_processor_loop())
+    except KeyboardInterrupt:
+        logger.info("Knowledge processor stopped by user")
+    except Exception as e:
+        logger.error(f"Fatal error in knowledge processor: {str(e)}")
+        sys.exit(1)
+
+