Configure helix and ruff

- Make helix use ruff-lsp and pyright
- Configure ruff to my specifications
- Tweak a helix theme color or two

.config/helix/languages.toml

@@ -0,0 +1,12 @@
+[[language]]
+name = "python"
+roots = ["pyproject.toml"]
+language-servers = ["pyright", "ruff"]
+auto-format = true
+
+[language-server.pyright]
+command = "pyright-langserver"
+args = ["--stdio"]
+
+[language-server.ruff]
+command = "ruff-lsp"