feat: add install handler and related logic

- Mako is now a core dependency
- therefore no more 'email' extra
- add `get_install_handler()` method for app handler
- add `render_mako_template()` method for app handler
- add `resource_path()` method for app handler
- install handler thus far can:
  - confirm db connection
  - make appdir plus config/scripts:
    - wutta.conf
    - web.conf
    - upgrade.sh
  - upgrade db schema to create tables
  - from there web app can run, create admin user
- quick start docs now describe "generated code" option

pyproject.toml

@@ -28,6 +28,7 @@ requires-python = ">= 3.8"
 dependencies = [
         'importlib-metadata; python_version < "3.10"',
         "importlib_resources ; python_version < '3.9'",
+        "Mako",
         "progress",
         "python-configuration",
         "typer",
@@ -36,7 +37,6 @@ dependencies = [
 
 [project.optional-dependencies]
 db = ["SQLAlchemy<2", "alembic", "alembic-postgresql-enum", "passlib"]
-email = ["Mako"]
 docs = ["Sphinx", "sphinxcontrib-programoutput", "enum-tools[sphinx]", "furo"]
 tests = ["pytest-cov", "tox"]