Fix missing dependencies and directories for Debian build

- Add psutil dependency to pyproject.toml and debian/control
- Fix pyproject.toml license format (use string instead of table)
- Create missing directories referenced in .install files:
  - templates/, chroot.d/, mounts/ for filesystem package
  - default-configs/ for configs package
  - docs/plugins/ for plugins package
  - dev/, docs/api/, include/, scripts/dev/ for dev package
  - cache-plugins/, cache.d/, docs/cache/ for cache package
- Add placeholder README.md files to prevent empty directories
- Update CI dependencies to include python3-psutil

Fixes:
- ModuleNotFoundError: No module named 'psutil' in performance.py
- Missing files errors in dh_install step
- pyproject.toml license deprecation warnings

Ready for successful Debian package build!

pyproject.toml

@@ -11,7 +11,7 @@ authors = [
 ]
 readme = "README.md"
 requires-python = ">=3.9"
-license = {text = "GPL-2.0-or-later"}
+license = "GPL-2.0-or-later"
 keywords = ["debian", "mock", "chroot", "build", "environment", "packaging"]
 classifiers = [
     "Development Status :: 3 - Alpha",
@@ -29,6 +29,7 @@ dependencies = [
     "pyyaml>=6.0",
     "jinja2>=3.0.0",
     "requests>=2.25.0",
+    "psutil>=5.8.0",
 ]
 
 [project.urls]