chore(root): remove project planning markdown and outdated configuration files

Remove extensive PLAN.md, management scripts, and lock files that are no longer needed.

pyproject.toml

@@ -1,40 +0,0 @@
-[project]
-name = "backend"
-version = "0.1.0"
-description = ""
-readme = "README.md"
-requires-python = ">=3.13"
-license = { text = "MIT" }
-dependencies = [
-    "django>=6.0.5",
-    "django-environ>=0.13.0",
-    "django-jazzmin==3.0.1",
-    "whitenoise>=6.12.0",
-    "psycopg[binary]",
-    "dj-database-url>=3.1.2",
-    "gunicorn>=26.0.0",
-    "django-tailwind-cli>=4.6.2",
-    "django-htmx>=1.27.0"
-]
-
-[tool.ruff]
-line-length = 88
-target-version = "py313"
-
-[tool.ruff.lint]
-select = [
-    "E",  # pycodestyle errors
-    "W",  # pycodestyle warnings
-    "F",  # pyflakes
-    "I",  # isort
-    "B",  # flake8-bugbear
-    "C4", # flake8-comprehensions
-    "UP", # pyupgrade
-]
-ignore = [
-    "E501",  # line too long, handled by formatter
-    "B008",  # do not perform function calls in argument defaults
-]
-
-[tool.ruff.lint.isort]
-known-first-party = ["config"]