feat: initial fish shell configuration

- Core config layered on CachyOS base with Catppuccin Mocha theming
- Fisher plugins: fzf.fish, catppuccin, autopair, replay, puffer-fish, magic-enter, spark
- Smart CLI wrappers with fallbacks (bat, lsd, btop, dust, prettyping)
- Custom functions: git, docker, network, kitty, AI session management
- Extensive abbreviation system for keyboard-driven workflows
- Secrets/local sourcing pattern for private and machine-specific config
- README with full documentation and personalization guide
- AGPLv3+ license with copyright headers on all source files

functions/tmux-clean.fish

@@ -0,0 +1,17 @@
+# Copyright (C) 2026 Rootiest
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+function tmux-clean --description 'Kill all tmux sessions except the current one'
+    # Get a list of all session names that are NOT currently attached
+    set sessions (tmux list-sessions -F '#{session_name} #{session_attached}' | string match -rv ' 1$' | string split -f1 ' ')
+
+    if test -n "$sessions"
+        for session in $sessions
+            echo "Stopping session: $session"
+            tmux kill-session -t "$session"
+        end
+        echo "Clean-up complete."
+    else
+        echo "No detached sessions to clean."
+    end
+end