chore(fish): Update env files

.fish/README.md

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+# Exported Fish Environment: ros2-assignments
+
+This directory contains a self-contained Fish shell environment that can be used
+without requiring the original Fish configuration.
+
+## Files Structure
+```
+.fish/
+├── activate.fish    # Main environment configuration
+└── README.md        # This file
+```
+
+## Usage
+
+### Automatic Activation (Recommended)
+The environment will automatically activate when you `cd` into this directory
+if your Fish shell is configured with the auto-activation feature that checks
+for `.fish/activate.fish`.
+
+### Manual Activation
+To manually activate the environment, run from the project root:
+```bash
+source ./.fish/activate.fish
+```
+
+### Deactivation
+To deactivate the environment, run:
+```bash
+env deactivate
+```
+
+Or simply `cd` to a different directory if using auto-activation.
+
+## What This Environment Provides
+
+- Custom prompt showing the environment name
+- Environment-specific aliases and functions
+- Custom environment variables
+- Automatic cleanup when deactivated
+
+## Requirements
+
+- Fish shell
+- If this is a ROS2 environment: `bass` plugin (`fisher install edc/bass`)
+
+## Sharing
+
+This environment is completely self-contained. You can:
+1. Copy this directory to another machine
+2. Share it with other Fish shell users
+3. Version control it with your project (add .fish/ to your repo)
+
+The environment will work on any system with Fish shell, regardless of whether
+they have the original environment management system installed.
+
+## Auto-activation Setup
+
+To enable auto-activation for .fish/activate.fish, add this to your Fish config.fish:
+```fish
+function check_and_source_activate
+  if test -f (pwd)/.fish/activate.fish
+    source (pwd)/.fish/activate.fish
+  elif test -f (pwd)/activate.fish
+    source (pwd)/activate.fish
+  end
+end
+
+function cd
+  builtin cd $argv && check_and_source_activate
+end
+```