Add working Dockerfile and fix plan to reflect Tampio's Python roots

PLAN.md

@@ -1,6 +1,6 @@
 # Tampiorama — Project Plan
 
-This is a project plan for project that's meaning is to be open source showcase for Tampio, the Finnish natural-language OOP language that compiles to JavaScript.
+This is a project plan for open source showcase for Tampio, the Finnish natural-language OOP language. Tampio is a Python-based compiler that takes Finnish-syntax source files and compiles them to JavaScript.
 
 ## Project Goals
 
@@ -23,15 +23,17 @@ tampiorama/
     ├── basics/                ← factorial, fibonacci, hello world
     ├── data-structures/       ← lists, maps
     ├── strings/
-    ├── async/                 ← Promise/async usage
+    ├── async/                 ← async/Promise in the compiled JS output
     └── program/               ← small "real" program
 ```
 
 ## Docker
 
-- Base image: Debian or Ubuntu (libvoikko available via apt)
-- Installs: `libvoikko-dev`, Node.js, `tampio` (npm)
-- Goal: `docker run` gives a working Tampio environment with no manual setup
+- Base image: Ubuntu 24.04
+- Installs: `libvoikko-dev`, `voikko-fi`, Python 3, `python3-libvoikko`, clones tampio from GitHub
+- Note: Tampio is not on PyPI or npm — installed directly from source
+- A `/usr/local/bin/tampio` wrapper makes it callable as a plain command
+- Goal: `docker compose run --rm tampio` gives a working shell with no manual setup
 
 ## Open Questions