Adopt mise for development workflows

- Lock Python and uv versions with mise
- Add unified sync, app, test, lint, format, and typecheck tasks
- Update development documentation and strengthen type handling

CONTRIBUTING.md

@@ -9,17 +9,18 @@ bugs or coordinate consequential changes.
 
 ## Development setup
 
-The project requires Python 3.13 or newer and
-[uv](https://docs.astral.sh/uv/):
+The project uses [mise](https://mise.jdx.dev/) to install its locked Python and
+uv versions and to provide its development tasks:
 
 ```bash
 git clone https://git.s1q.dev/phg/hosts.git
 cd hosts
-uv sync
-uv run hosts
+mise install
+mise run sync
+mise run app
 ```
 
-`uv run hosts` starts the real application and reads `/etc/hosts`. Stay in
+`mise run app` starts the real application and reads `/etc/hosts`. Stay in
 Read-only Mode unless you deliberately intend to exercise privileged behavior
 on your machine. Automated tests must use mocks and temporary files instead.
 
@@ -80,23 +81,21 @@ Treat any test capable of touching the real system file as a defect.
 Run the narrowest relevant test while developing. Examples:
 
 ```bash
-uv run pytest tests/test_parser.py
-uv run pytest tests/test_manager.py
-uv run pytest tests/test_main.py
+mise run test -- tests/test_parser.py
+mise run test -- tests/test_manager.py
+mise run test -- tests/test_main.py
 ```
 
 Before handing off any change, run the complete validation suite:
 
 ```bash
-uv run pytest
-uv run ruff check .
-uv run ruff format --check .
+mise run check
 ```
 
 Apply formatting with:
 
 ```bash
-uv run ruff format .
+mise run format
 ```
 
 Add or update tests for changed behavior. Test user-reachable workflows at the