capi: allow editable installs

By also inspecting site-packages when importing the shared library,
editable installs should be better supported. Typically, the shared
library is not installed in the source directory during an editable
install.

Author: stickies-v

src/pbk/capi/bindings.py

@@ -7,17 +7,21 @@
 #
 import ctypes
 import ctypes.util
+import site
+from importlib import resources
 from pathlib import Path
 
 
 def _find_bitcoinkernel_lib():
-    # Check relative ../_libs/ directory
-    script_dir = Path(__file__).parent
-    if (matches := list((script_dir.parent / "_libs").glob("*bitcoinkernel*"))):
+    resources_paths = [resources.files("pbk")]
+    # Adding site packages makes this work in editable mode with scikit-build-core
+    site_packages_paths = [Path(p) / "pbk" for p in site.getsitepackages()]
+    for pkg_path in [*resources_paths, *site_packages_paths]:
+        matches = list((pkg_path / "_libs").glob('*bitcoinkernel*'))
         if len(matches) == 1:
             return str(matches[0])
-        raise RuntimeError(f"Found multiple libbitcoinkernel candidates: {matches}")
-        
+        if matches:
+            raise RuntimeError(f"Found multiple libbitcoinkernel candidates: {matches}")
     raise RuntimeError(
         "Could not find libbitcoinkernel. Please re-run `pip install`."
     )