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/_autopair_insert_same.fish

@@ -0,0 +1,20 @@
+function _autopair_insert_same --argument-names key
+    set --local buffer (commandline)
+    set --local index (commandline --cursor)
+    set --local next (string sub --start=(math $index + 1) --length=1 -- "$buffer")
+
+    if test (math (count (string match --all --regex -- "$key" "$buffer")) % 2) = 0
+        test $key = $next && commandline --cursor (math $index + 1) && return
+
+        commandline --insert -- $key
+
+        if test $index -lt 1 ||
+                contains -- (string sub --start=$index --length=1 -- "$buffer") "" " " $autopair_left &&
+                contains -- $next "" " " $autopair_right
+            commandline --insert -- $key
+            commandline --cursor (math $index + 1)
+        end
+    else
+        commandline --insert -- $key
+    end
+end