feat: switch container user to root and add welcome bootstrap for dev environment

- Change container user from 'ubuntu' to 'root' in Dockerfile and docker-compose config
- Set working directory to /home/retoor/projects/snek and inject SNEK_UID environment variable
- Add root password setup and copy terminal bootstrap files (entry script, .welcome.txt) into container image
- Refactor compose exec/start methods to capture stdout/stderr via pipes and handle empty output gracefully
- Remove strict returncode check in exec method, replacing with debug print for non-zero exits

terminal/.welcome.txt

@@ -0,0 +1,47 @@
+👋 Welcome to your custom Ubuntu development environment!
+
+This container is pre-configured with a rich set of tools to help you hit the ground running:
+
+🔧 Development Libraries & Tools:
+
+Full support for building and debugging C/C++ and Python code
+
+Libraries for SSL, readline, SQLite, zlib, bz2, ffi, lzma, and JSON-C
+
+Valgrind for memory debugging and profiling
+
+🐍 Python:
+
+Python 3 with pip and virtual environment support (venv)
+
+🦀 Rust:
+
+Rust installed with the nightly toolchain via rustup
+
+🛠 Command-line Essentials:
+
+vim, tmux, htop, git, curl, wget, xterm, ack, and more
+
+💬 Networking & Communication:
+
+irssi for IRC and lynx for browsing from the terminal
+
+📦 Custom Tool Installed:
+
+Latest version of AI vibe coding tool r is installed from the 
+retoor.molodetz.nl repository. 
+
+To get started, open a new terminal and type "r" to launch the tool.
+
+Configure ~/.rcontext.txt to describe it's behavior. It can be a friend
+or a whatever you like. 
+
+🔐 Credentials:
+
+Default root password is set to: root (please change it if needed)
+
+🗂 Custom Terminal Files:
+
+Files from ./terminal/ have been copied to your home directory (/root/)
+
+Enjoy hacking in your personalized command-line workspace!