chore: add Zed project config, .editorconfig and shared pyright settings

- .zed/settings.json: ruff + basedpyright for Python (no format on save, the
  tree is not ruff-format clean), ESLint fixes then Prettier for the frontend,
  scan exclusions for caches and build outputs, .jwt_secret_key as private
- .zed/tasks.json: dev services, API, worker, frontend, pytest/vitest for the
  current file or test, linting, uv lock + requirements export
- .zed/debug.json: debugpy targets matching .vscode/launch.json
- .editorconfig: whitespace rules for every editor
- [tool.pyright] in pyproject.toml: venv, import root and excludes shared by
  pyright, basedpyright and Pylance
- .gitignore: track only the shared files under .zed/
- CONTRIBUTING: editor setup section; fix the stale ESLint config path

.gitignore

@@ -195,6 +195,11 @@ docsgpt/static/
 node_modules/
 .vscode/settings.json
 .vscode/sftp.json
+# Zed: the shared project config is tracked, anything else under .zed/ is local
+.zed/*
+!.zed/settings.json
+!.zed/tasks.json
+!.zed/debug.json
 /models/
 model/