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

conf.d/fish_frozen_key_bindings.fish

@@ -0,0 +1,14 @@
+# This file was created by fish when upgrading to version 4.3, to migrate
+# the 'fish_key_bindings' variable from its old default scope (universal)
+# to its new default scope (global).  We recommend you delete this file
+# and configure key bindings in ~/.config/fish/config.fish if needed.
+
+# set --global fish_key_bindings fish_default_key_bindings
+
+# Prior to version 4.3, fish shipped an event handler that runs
+# `set --universal fish_key_bindings fish_default_key_bindings`
+# whenever the fish_key_bindings variable is erased.
+# This means that as long as any fish < 4.3 is still running on this system,
+# we cannot complete the migration.
+# As a workaround, erase the universal variable at every shell startup.
+set --erase --universal fish_key_bindings