Use setenv in launcher scripts, add requirements.txt and missing .sh scripts

platz.bat/platz.sh now derive PLATZ via setenv instead of hardcoded
paths, matching the Standard Programm Template already applied to
setenv/install_py/activate_venv/get_cmd. Added the missing .sh
counterparts to those .bat scripts, an empty requirements.txt for
install_py to install (project only uses the stdlib), and ignore
entries for .venv/, out/, .vscode/, *.swp.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

README.md

@@ -7,14 +7,14 @@ using a small custom GA framework, and writes the result to text/CSV output file
 
 **This is Python 2 code** (print statements, `ConfigParser`, `sets.Set`, `UserList`,
 `string.split`, old-style `raise Exception, "msg"`, `xrange`, `dict.has_key`,
-`dict.iteritems`). It needs a Python 2 interpreter; there are no third-party dependencies
-(standard library only).
+`dict.iteritems`). There are no third-party dependencies (standard library only), so
+`requirements.txt` is empty — it exists only so `bin/install_py` has something to install.
 
 ## Project structure
 
 ```
 platz/
-├── bin/           # launcher scripts (bash + Windows batch)
+├── bin/           # environment + launcher scripts (.bat + .sh pairs)
 ├── cfg/           # GA cycle definition and penalty scheme
 ├── libs/          # the two Python modules (ga.py, Strukturdaten.py, platz.py)
 └── work/          # per-run input (table layout, guest list) and output
@@ -29,29 +29,48 @@ platz/
 
 ## Setup
 
-1. Install a Python 2 interpreter (2.4+; no `pip install` needed, standard library only).
-2. Edit the hardcoded paths at the top of the launcher script for your platform:
-   - `bin/run` (bash): `PLATZ=/Users/sm/develop/python/platz`
-   - `bin/run.bat` (Windows): `PLATZ=h:\develop\python\platz` and `PYTHONSHELL=l:\tools\i486_nt\python24`
+1. Install a Python interpreter (`py` on Windows / `python3` on Linux/macOS must be on
+   `PATH`).
+2. Run the installer for your platform to create a `.venv` and install `requirements.txt`:
 
-   Point `PLATZ` at wherever you checked out this repository.
+   ```bat
+   :: Windows
+   bin\install_py.bat
+   ```
+
+   ```bash
+   # Linux/macOS
+   bin/install_py.sh
+   ```
+
+All `bin/` scripts derive `PLATZ` automatically from their own location (no path editing
+required) by calling `setenv.bat`/`setenv.sh` first.
 
 ## Running
 
-From a shell:
+```bat
+:: Windows
+bin\activate_venv.bat
+bin\platz.bat
+```
 
 ```bash
 # Linux/macOS
-source bin/run
+source bin/activate_venv.sh
+bin/platz.sh
 ```
 
-```bat
-:: Windows
-bin\run.bat
-```
+`bin/platz.bat` / `bin/platz.sh` call `setenv` to set `PLATZ`, `PLATZ_CFG`, `PLATZ_LIBS`,
+`PLATZ_WORK`, `PLATZ_IN`, `PLATZ_OUT`, add `PLATZ_LIBS` to `PYTHONPATH`, and then run
+`libs/platz.py`.
 
-The launcher sets `PLATZ_CFG`, `PLATZ_LIBS`, `PLATZ_WORK`, adds `PLATZ_LIBS` to
-`PYTHONPATH`, and runs `libs/platz.py`.
+Other helper scripts (`bin/setenv.*`, `bin/get_cmd.*`) follow the same environment
+convention:
+
+- `setenv` — sets all `PLATZ_*` environment variables and creates missing folders; sourced
+  by every other script, not normally called directly.
+- `activate_venv` — activates the `.venv` created by `install_py`.
+- `get_cmd` — opens a new shell with the `PLATZ_*` environment already set.
 
 ### Configuring a run