fix(config): Add html_static_path and templates_path defaults

why: merge_sphinx_config() was missing these two keys, so downstream
projects lost their _static/ directory (logos, custom CSS, images) and
_templates/ overrides from the build output. Discovered when migrating
tmuxp: logo 404'd because docs/_static/img/tmuxp.svg was never copied.

Both paths are standard conventions every gp-sphinx consumer uses.
Sphinx silently ignores missing directories in these lists, so the
defaults are safe for projects that don't have one or both.

what:
- defaults.py: add DEFAULT_HTML_STATIC_PATH = ["_static"]
- defaults.py: add DEFAULT_TEMPLATES_PATH = ["_templates"]
- config.py: import and wire both into merge_sphinx_config() conf dict
- tests/test_config.py: update test_merge_sphinx_config_html_paths to
  assert defaults are present instead of asserting they're absent

Author: tony

packages/gp-sphinx/src/gp_sphinx/config.py

@@ -45,6 +45,7 @@
     DEFAULT_COPYBUTTON_PROMPT_TEXT,
     DEFAULT_COPYBUTTON_REMOVE_PROMPTS,
     DEFAULT_EXTENSIONS,
+    DEFAULT_HTML_STATIC_PATH,
     DEFAULT_MYST_EXTENSIONS,
     DEFAULT_MYST_HEADING_ANCHORS,
     DEFAULT_NAPOLEON_GOOGLE_DOCSTRING,
@@ -57,6 +58,7 @@
     DEFAULT_SPHINX_FONT_PRELOAD,
     DEFAULT_SPHINX_FONTS,
     DEFAULT_SUPPRESS_WARNINGS,
+    DEFAULT_TEMPLATES_PATH,
     DEFAULT_THEME,
     DEFAULT_THEME_OPTIONS,
     DEFAULT_TOC_OBJECT_ENTRIES_SHOW_PARENTS,
@@ -368,6 +370,9 @@ def merge_sphinx_config(
         "master_doc": "index",
         # Source
         "source_suffix": dict(DEFAULT_SOURCE_SUFFIX),
+        # Static files and templates
+        "html_static_path": list(DEFAULT_HTML_STATIC_PATH),
+        "templates_path": list(DEFAULT_TEMPLATES_PATH),
         # Theme (gp-sphinx child theme provides sidebars, templates, CSS, JS)
         "html_theme": DEFAULT_THEME,
         "html_theme_path": [],

packages/gp-sphinx/src/gp_sphinx/defaults.py

@@ -122,6 +122,28 @@
 'markdown'
 """
 
+DEFAULT_HTML_STATIC_PATH: list[str] = ["_static"]
+"""Default path(s) to project-specific static files (CSS, images, JS).
+
+Resolved relative to the docs source directory (``docs/_static/``).
+
+Examples
+--------
+>>> DEFAULT_HTML_STATIC_PATH
+['_static']
+"""
+
+DEFAULT_TEMPLATES_PATH: list[str] = ["_templates"]
+"""Default path(s) to Jinja2 template overrides.
+
+Resolved relative to the docs source directory (``docs/_templates/``).
+
+Examples
+--------
+>>> DEFAULT_TEMPLATES_PATH
+['_templates']
+"""
+
 DEFAULT_PYGMENTS_STYLE: str = "monokai"
 """Default Pygments syntax highlighting style."""
 

tests/test_config.py

@@ -373,14 +373,14 @@ def test_merge_sphinx_config_copybutton_continuation() -> None:
 
 
 def test_merge_sphinx_config_html_paths() -> None:
-    """Theme asset paths stay opt-in for minimal consumers."""
+    """Static and template paths default to standard locations; extras are opt-in."""
     result = merge_sphinx_config(
         project="test",
         version="1.0",
         copyright="2026",
     )
-    assert "templates_path" not in result
-    assert "html_static_path" not in result
+    assert result["html_static_path"] == ["_static"]
+    assert result["templates_path"] == ["_templates"]
     assert "html_favicon" not in result
     assert "html_extra_path" not in result