Flatten repo structure: move crawler/ to root, remove vqa/ and immoweb/

The crawler subdirectory was the only active project. Moving it to the
repo root simplifies paths and removes the unnecessary nesting. The
vqa/ and immoweb/ directories were legacy/unused and have been removed.

Updated .drone.yml, .gitignore, .claude/ docs, and skills to reflect
the new flat structure.

crawler/utils/redis_lock.py

@@ -1,50 +0,0 @@
-"""Redis-based distributed locking for task coordination."""
-import logging
-import os
-from contextlib import contextmanager
-from typing import Generator
-
-import redis
-
-logger = logging.getLogger("uvicorn.error")
-
-
-def get_redis_client() -> redis.Redis:
-    """Get Redis client from Celery broker URL."""
-    broker_url = os.getenv("CELERY_BROKER_URL", "redis://localhost:6379/0")
-    return redis.from_url(broker_url, decode_responses=True)
-
-
-@contextmanager
-def redis_lock(
-    lock_name: str, timeout: int = 3600 * 4
-) -> Generator[bool, None, None]:
-    """Distributed lock using Redis.
-
-    Args:
-        lock_name: Unique name for the lock
-        timeout: Lock expiration time in seconds (default: 4 hours)
-
-    Yields:
-        bool: True if lock was acquired, False otherwise
-
-    Example:
-        with redis_lock("scrape_listings") as acquired:
-            if not acquired:
-                logger.warning("Another scrape is already running")
-                return
-            # ... do work ...
-    """
-    client = get_redis_client()
-    lock_key = f"lock:{lock_name}"
-
-    # Try to acquire the lock
-    acquired = client.set(lock_key, "1", nx=True, ex=timeout)
-
-    try:
-        yield bool(acquired)
-    finally:
-        # Release the lock only if we acquired it
-        if acquired:
-            client.delete(lock_key)
-            logger.info(f"Released lock: {lock_name}")