fix: apply aishell review findings

- fix vim-plug URL typo (juneguyen -> junegunn) in install.zsh
- fix recent-dirs path to ~/.chpwd-recent-dirs in ais
- remove dead plugins (cdselect, fileselect, histselect) superseded by ais
- fix .gitignore to properly exclude target/ dirs

.gitignore

@@ -4,7 +4,7 @@
 Cargo.lock
 node_modules
 package-lock.json
-/target
+target/
 /dist
 /tmp
 *.swp