Hygiene pass: fix stale paths, drop dead config, trim noise

- .zshrc: gate bun/grok blocks on dir existence; use $BUN_INSTALL for
  completions path (was hardcoded /home/lkraven); drop dead
  lk-tools/fzf path entry
- zellij: remove autogenerated banner referencing a Linux backup path
- aider.conf.yml: trim to active settings (was 459-line sample dump)

home_root/.zshrc

@@ -1,7 +1,6 @@
 #extend path
 path=(~/bin $path)
 path=(~/.local/bin $path)
-path=(~/.cache/lk-tools/fzf/bin $path)
 
 # Enable Powerlevel10k instant prompt. Should stay close to the top of ~/.zshrc.
 # Initialization code that may require console input (password prompts, [y/n]
@@ -130,22 +129,25 @@ fi
 
 export STM32_PRG_PATH=/Applications/STMicroelectronics/STM32Cube/STM32CubeProgrammer/STM32CubeProgrammer.app/Contents/MacOs/bin
 
-# bun completions
-[ -s "/home/lkraven/.bun/_bun" ] && source "/home/lkraven/.bun/_bun"
+# bun (only if installed)
+if [ -d "$HOME/.bun" ]; then
+  export BUN_INSTALL="$HOME/.bun"
+  export PATH="$BUN_INSTALL/bin:$PATH"
+  [ -s "$BUN_INSTALL/_bun" ] && source "$BUN_INSTALL/_bun"
+fi
 
-# bun
-export BUN_INSTALL="$HOME/.bun"
-export PATH="$BUN_INSTALL/bin:$PATH"
-
-# >>> grok installer >>>
-export PATH="$HOME/.grok/bin:$PATH"
-fpath=(~/.grok/completions/zsh $fpath)
-autoload -Uz compinit && compinit -C
-# <<< grok installer <<<
+# grok (only if installed; avoids a second compinit when absent)
+if [ -d "$HOME/.grok" ]; then
+  export PATH="$HOME/.grok/bin:$PATH"
+  fpath=(~/.grok/completions/zsh $fpath)
+  autoload -Uz compinit && compinit -C
+fi
 
 # dotnet
 export DOTNET_ROOT="$HOME/.dotnet"
 export PATH="$DOTNET_ROOT:$PATH"
 
-# kimi-code
-export PATH="/home/lkraven/.kimi-code/bin:$PATH"
+# kimi-code (only if installed)
+if [ -d "$HOME/.kimi-code" ]; then
+  export PATH="$HOME/.kimi-code/bin:$PATH"
+fi