Speed up shell startup: remove duplicate compinit, lazy-load pyenv/nvm

- Remove manual compinit in .zshrc (oh-my-zsh already handles it),
  eliminating a redundant ~350ms call
- Lazy-load pyenv init (~710ms) until first use, matching the existing
  kubectl lazy-load pattern
- Lazy-load nvm init for when it gets installed in the future

dot_oh-my-zsh/custom/tools/nvm.zsh

@@ -1,6 +1,14 @@
 # NVM (Node Version Manager) configuration
 # Auto-loaded by oh-my-zsh from $ZSH_CUSTOM/tools/
+# Lazy-loaded: defers nvm init until first use
 
 export NVM_DIR="$HOME/.nvm"
-[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"
-[ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"
+
+if [[ -s "$NVM_DIR/nvm.sh" ]]; then
+    function nvm() {
+        unfunction nvm
+        \. "$NVM_DIR/nvm.sh"
+        [ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"
+        nvm "$@"
+    }
+fi