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.

services/floorplan_detector.py

@@ -0,0 +1,47 @@
+"""Floorplan detector service - OCR-based square meter detection."""
+import asyncio
+from models import Listing
+from rec import floorplan
+from repositories.listing_repository import ListingRepository
+from tqdm.asyncio import tqdm
+import multiprocessing
+
+# Use a quarter of available CPUs to avoid starving other processes
+MAX_OCR_WORKERS = max(1, multiprocessing.cpu_count() // 4)
+
+
+async def detect_floorplan(repository: ListingRepository) -> None:
+    """Detect square meters from floorplan images for all listings."""
+    listings = await repository.get_listings()
+    semaphore = asyncio.Semaphore(MAX_OCR_WORKERS)
+
+    updated_listings = [
+        listing
+        for listing in await tqdm.gather(
+            *[_calculate_sqm_ocr(listing, semaphore) for listing in listings]
+        )
+        if listing is not None
+    ]
+    await repository.upsert_listings(updated_listings)
+
+
+async def _calculate_sqm_ocr(
+    listing: Listing, semaphore: asyncio.Semaphore
+) -> Listing | None:
+    """Calculate square meters from floorplan images using OCR."""
+    if listing.square_meters is not None:
+        return None
+    if not listing.floorplan_image_paths:
+        listing.square_meters = 0
+        return listing
+    sqms: list[float] = []
+    for floorplan_path in listing.floorplan_image_paths:
+        async with semaphore:
+            estimated_sqm, _ = await asyncio.to_thread(
+                floorplan.calculate_ocr, floorplan_path
+            )
+            if estimated_sqm is not None:
+                sqms.append(estimated_sqm)
+    max_sqm = max(sqms, default=0)  # try once, if we fail, keep as 0
+    listing.square_meters = max_sqm
+    return listing