add Sphinx documentation

docs/conf.py

@@ -0,0 +1,39 @@
+"""Sphinx configuration for the nexus-sync documentation."""
+
+import os
+import sys
+
+# Make the package importable for autodoc (sources live under src/).
+sys.path.insert(0, os.path.abspath("../src"))
+
+project = "nexus-sync"
+author = "nexus-sync"
+copyright = "2026, nexus-sync"
+release = "0.1.0"
+
+extensions = [
+    "myst_parser",
+    "sphinx.ext.autodoc",
+    "sphinx.ext.autosummary",
+    "sphinx.ext.napoleon",
+    "sphinx.ext.viewcode",
+]
+
+# Pull docstrings even from undocumented members so the API pages are useful
+# while docstring coverage grows.
+autosummary_generate = True
+autodoc_default_options = {
+    "members": True,
+    "undoc-members": True,
+    "show-inheritance": True,
+}
+autodoc_typehints = "description"
+
+# MyST so the existing Markdown guides render as-is.
+myst_enable_extensions = ["colon_fence", "deflist"]
+source_suffix = {".md": "markdown", ".rst": "restructuredtext"}
+
+exclude_patterns = ["_build", ".DS_Store", "Thumbs.db", "archive"]
+
+html_theme = "furo"
+html_title = "nexus-sync"