Update project configuration and code structure

- Added '*.o' to .gitignore to exclude object files from version control.
- Modified Dockerfile to specify the application directory for Uvicorn.
- Updated setup.py to reflect the new source directory structure for Cython extensions.
- Adjusted E2E Docker Compose command to include the application directory.
- Refined type hints in ApiClient and Security classes for better clarity and consistency.

These changes enhance the project's organization and improve the build process.

src/security.pxd

@@ -2,19 +2,19 @@ from credentials cimport Credentials
 
 cdef class Security:
     @staticmethod
-    cdef encrypt_to(input_stream, key)
+    cdef bytes encrypt_to(bytes input_bytes, str key)
 
     @staticmethod
-    cdef decrypt_to(input_bytes, key)
+    cdef bytes decrypt_to(bytes input_bytes, str key)
 
     @staticmethod
-    cdef get_hw_hash(str hardware)
+    cdef str get_hw_hash(str hardware)
 
     @staticmethod
-    cdef get_api_encryption_key(Credentials credentials, str hardware_hash)
+    cdef str get_api_encryption_key(Credentials credentials, str hardware_hash)
 
     @staticmethod
-    cdef get_resource_encryption_key()
+    cdef str get_resource_encryption_key()
 
     @staticmethod
-    cdef calc_hash(str key)
+    cdef str calc_hash(str key)