refactor: ✨ (#418)

* refactor: ✨ move in one commit

Eveything in modules should probably be changed to `exported` defs.
The idea is to move everything first to keep proper history.

* refactor: 📝 add modules readme (wip)

* refactor: ✨ small move

* refactor: 📝 changed nestring, updated modules readme

* refactor: 📝 to document or not to document

* fix: 🐛 themes

replaced the template to use `main` and regenerated them
from lemnos themes.

* Revert "fix: 🐛 themes"

This reverts commit 4918d3633c8d2d81950a0ed0cfd9eb84241bc886.

* refactor: ✨ introduce sourced

- Created a source `root` in which sourcable demos are stored.
  Some might get converted to modules later on.
- Moved some files to bin too.

* fix: 🐛 fehbg.nu

* fix: 🐛 modules/after.nu

* moved some other stuff around

---------

Co-authored-by: Darren Schroeder <343840+fdncred@users.noreply.github.com>

modules/virtual_environments/auto-venv/README.md

@@ -0,0 +1,33 @@
+# Auto virtual environment scripts
+
+The scripts in this directory activate virtual environments whenever you cd into a directory with a "trigger" file 
+
+## Usage
+
+1. set `$env.AUTO_VENV_TRIGGER` to the name of a script file
+1. import `auto-venv` into your environment
+1. cd into a folder that contains your trigger file
+
+ex.
+```nu
+# config.nu
+
+export-env {
+    let-env AUTO_VENV_TRIGGER = '__auto-venv.nu'
+
+    source-env ~/path/to/nu_scripts/virtual_environments/auto-venv/auto-venv.nu
+}
+
+use ~/path/to/nu_scripts/virtual_environments/auto-venv/auto-venv.nu *
+```
+
+When `auto-venv` detects that a file of that name exists in the folder you cd'ed into (or one of it's parents), it will automatically enable an overlay (as defined by the trigger file).
+
+An example overlay for python venv is in `./venvs`
+
+NOTE: the trigger file *must* export a custom command called `auto-venv-on-enter` that takes in the `$env` (this is the environment *before* the overlay was enabled).  
+
+
+## Limitations
+
+- Due to limitations with overlay naming, you cannot nest auto-venv triggers, even for separate languages / toolchains