Make server dotfiles generic: single servers/ folder instead of per-host

Consolidated server/<host>/ into one generic servers/ set applied to any
host. Baseline chosen as the superset of the per-host configs:
.zshrc (agnoster + kubectl), identical .vimrc, standard .bashrc, fuller
htoprc, and the shared neofetch config.

install.sh now deploys servers/ unconditionally (no hostname matching);
removed the --host flag. README updated accordingly.

servers/.zshrc

@@ -0,0 +1,10 @@
+ZSH_DISABLE_COMPFIX=true
+
+export ZSH=$HOME/.oh-my-zsh
+
+ZSH_THEME="agnoster"
+export TERM=xterm-256color
+
+plugins=(git docker docker-compose zsh-autosuggestions kubectl)
+
+source $ZSH/oh-my-zsh.sh