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.

models/passkey_credential.py

@@ -0,0 +1,13 @@
+from datetime import datetime
+
+from sqlmodel import SQLModel, Field
+
+
+class PasskeyCredential(SQLModel, table=True):
+    id: int | None = Field(default=None, primary_key=True)
+    credential_id: str = Field(index=True, unique=True)
+    public_key: str
+    sign_count: int = Field(default=0)
+    transports: str | None = Field(default=None)  # JSON-encoded list
+    user_id: int = Field(foreign_key="user.id", index=True)
+    created_at: datetime = Field(default_factory=datetime.utcnow)