Rewrite CI to lint/typecheck/audit/test only; add HPC deployment path

- Replace the Docker build/publish CI stages with ruff (lint + format
  check), ty (type check), pip-audit, and pytest run directly against
  python:3.11-slim; Docker remains for manual/server deployment only.
- Swap black/pylint/mypy for ruff/ty across pyproject.toml, and fix
  every resulting lint, format, and type diagnostic in gallery/ and
  plotstyle/.
- Fix tests broken/stale from before the package restructuring: wrong
  `utils.*` import paths, mock patch targets pointed at the wrong
  module, and PDF-conversion tests still assuming ImageMagick instead
  of the current PyMuPDF-first path. Drop test_container.py (obsolete
  Docker-container smoke tests, fully superseded elsewhere).
- Add a plain-venv + systemd --user timer deployment path
  (deploy/systemd/) for HPC login nodes without a Docker daemon, where
  public_html is already served by existing infrastructure.
- Document both in CLAUDE.md, including running CI's checks locally
  before committing.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

gallery/builder.py

@@ -2,7 +2,8 @@
 
 import shutil
 from pathlib import Path
-from typing import Dict, Any, Optional, Union
+from typing import Any, Dict, Optional, Union
+
 from jinja2 import Environment, FileSystemLoader, Template
 
 from gallery.config import GalleryConfig
@@ -17,7 +18,6 @@ from gallery.utils.metadata import (
 )
 from gallery.utils.processing import (
     process_plot_files,
-    needs_update,
     render_gallery_page,
 )
 
@@ -39,13 +39,14 @@ def get_template(template_dir: Optional[Union[Path, str]] = None):
     if template_dir is None:
         # Use package-included template
         import gallery
+
         gallery_module_path = Path(gallery.__file__).parent
         template_dir = gallery_module_path / "templates"
 
     env = Environment(loader=FileSystemLoader(str(template_dir)))
 
-    env.filters['datetime_from_timestamp'] = datetime_from_timestamp
-    env.filters['strftime'] = strftime_filter
+    env.filters["datetime_from_timestamp"] = datetime_from_timestamp
+    env.filters["strftime"] = strftime_filter
 
     return env.get_template("gallery.html")
 
@@ -54,8 +55,8 @@ def build_gallery(
     config: GalleryConfig,
     source_dir: Path,
     web_dir: Path,
-    template: Template = None,
-    relative_path: Path = None,
+    template: Optional[Template] = None,
+    relative_path: Optional[Path] = None,
     inherited_metadata: Optional[Dict[str, Any]] = None,
 ) -> None:
     """
@@ -119,7 +120,7 @@ def build_gallery(
             subdir_web,
             template,
             subdir_relative,
-            current_metadata if config.inherit_from_parent else {}
+            current_metadata if config.inherit_from_parent else {},
         )
         subdir_names.append(subdir.name)
 
@@ -130,15 +131,11 @@ def build_gallery(
         items=items,
         subdirs=subdir_names,
         relative_path=relative_path,
-        metadata=current_metadata
+        metadata=current_metadata,
     )
 
 
-def copy_assets(
-    config: GalleryConfig,
-    assets_src: Optional[Path] = None,
-    verbose: bool = False
-) -> bool:
+def copy_assets(config: GalleryConfig, assets_src: Optional[Path] = None, verbose: bool = False) -> bool:
     """
     Copy assets to the web directory.
 
@@ -154,14 +151,13 @@ def copy_assets(
         if assets_src is None:
             # Use package-included assets
             import gallery
+
             gallery_module_path = Path(gallery.__file__).parent
             assets_src = gallery_module_path / "assets"
 
         if not assets_src.exists():
             if verbose:
-                print(
-                    f"Warning: Assets directory {assets_src} not found"
-                )
+                print(f"Warning: Assets directory {assets_src} not found")
             return False
 
         gallery_root = Path(config.web_folder) / config.plot_root
@@ -171,7 +167,7 @@ def copy_assets(
         # so any change to any JS/CSS file triggers a redeploy.
         sentinel_dst = assets_dst / "css" / "main.css"
         newest_src_mtime = max(
-            (f.stat().st_mtime for f in assets_src.rglob('*') if f.is_file()),
+            (f.stat().st_mtime for f in assets_src.rglob("*") if f.is_file()),
             default=0,
         )
         dst_mtime = sentinel_dst.stat().st_mtime if sentinel_dst.exists() else 0