Improve startup performance and reduce resource usage

- Defer elfeed auto-update timers until first use (was running at startup)
- Fix consult-project-function to handle nil project gracefully
- Remove duplicate delete-trailing-whitespace hook
- Remove redundant diff-hl find-file-hook (global-diff-hl-mode handles it)
- Reduce treemacs resource usage (lower git entries, disable filewatch)
- Make dired dotfiles-first sorting opt-in (C-c s to sort, C-c S to toggle)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lisp/init-ui.el

@@ -156,9 +156,8 @@
     (princ "  M-x ensure-cua-bindings\n")
     (princ "  M-x cua-mode (toggle off and on)\n")))
 
-;; Trailing whitespace
+;; Trailing whitespace visualization (deletion handled in init-editor.el)
 (setq show-trailing-whitespace t)
-(add-hook 'before-save-hook 'delete-trailing-whitespace)
 
 ;; Fill column indicator
 (setq-default display-fill-column-indicator-column 80)