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/save_claude_session.fish

@@ -0,0 +1,31 @@
+# Copyright (C) 2026 Rootiest
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+#!/usr/bin/env fish
+
+# 1. Read input and extract session ID
+set -l input (cat)
+set -l sid (echo $input | python3 -c "import sys,json; print(json.load(sys.stdin).get('session_id', ''))")
+set -l session_file ".claude_session"
+
+if test -n "$sid"
+    # 2. Save the session ID locally
+    echo "$sid" >$session_file
+
+    # 3. Smart .gitignore check
+    # We check if git even knows about this file. 
+    # If 'git check-ignore' returns 1, it means the file is NOT ignored.
+    if git rev-parse --is-inside-work-tree >/dev/null 2>&1
+        if not git check-ignore -q $session_file
+            # Append the filename to .gitignore
+            echo -e "\n# AI Session IDs\n$session_file" >>.gitignore
+            echo "Added $session_file to .gitignore"
+        end
+    end
+
+    # 4. Update universal variable
+    set -U LAST_CLAUDE_SESSION "$sid"
+end
+
+# MANDATORY: Every hook must output valid JSON
+echo '{}'