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/_puffer_fish_expand_buck.fish

@@ -0,0 +1,10 @@
+function _puffer_fish_expand_buck
+    if commandline --search-field >/dev/null
+        commandline --search-field --insert '$'
+    else if string match --quiet '!' -- "$(commandline --current-token)"
+        commandline --current-token ''
+        commandline -f history-token-search-backward
+    else
+        commandline --insert '$'
+    end
+end