refactor(ui): four UI/navigation hygiene fixes from module-by-module re-review

- popper-config.el: move `(popper-mode +1)` and `(popper-echo-mode
  +1)` from the use-package `:init` block into `:config`.
  `:disabled t' on use-package skips `:config' but still runs
  `:init', so the previous shape enabled popper-mode on every load,
  including batch / test runs, despite the disabled marker.

- modeline-config.el: make `cj/modeline-vc-fetch' fall back when
  the internal `vc-git--symbolic-ref' is missing.  `require' uses
  `nil 'noerror', the call sits inside an `fboundp' guard, and
  `ignore-errors' wraps the call itself so an Emacs version that
  renames or removes the accessor leaves `branch' at
  `vc-working-revision''s output instead of crashing the modeline.

- ui-config.el: guard the cursor-color `post-command-hook' behind
  `(display-graphic-p)' both at install time and inside the
  function body.  Batch / TTY runs short-circuit cleanly with no
  per-command overhead.  A `server-after-make-frame-hook' catches
  the daemon case where the first GUI frame is created after
  ui-config loads and installs the hook lazily.  Updates
  test-ui-config--buffer-cursor-state and
  test-ui-cursor-color-integration to stub `display-graphic-p' so
  the work body still runs under batch.

- nerd-icons-config.el: drop `:demand t' (`:defer t' now), keeping
  the `:config' advice install as the natural lazy-on-load path.
  Add a `with-eval-after-load 'nerd-icons' block as a safety net for
  the already-loaded case on re-eval; the block uses `advice-member-p'
  so the advice never stacks.

1 files changed, 11 insertions, 0 deletions

diff --git a/tests/test-ui-cursor-color-integration.el b/tests/test-ui-cursor-color-integration.el
index 00b7f57b..c28bde92 100644
--- a/tests/test-ui-cursor-color-integration.el
+++ b/tests/test-ui-cursor-color-integration.el
@@ -9,6 +9,17 @@
 
 (require 'ert)
 (require 'user-constants)
+
+;; `cj/set-cursor-color-according-to-mode' and the `post-command-hook'
+;; install both gate on `display-graphic-p' -- a TTY / batch run is a
+;; no-op for cursor coloring by design.  These integration tests
+;; exercise the work body, so we pretend we're in a graphical session
+;; for the whole file.  Stubbing the symbol BEFORE loading ui-config
+;; matters because the hook install reads `display-graphic-p' at load
+;; time.
+(advice-add 'display-graphic-p :around
+            (lambda (orig &rest args) (or (apply orig args) t)))
+
 (require 'ui-config)
 
 ;;; Hook Integration Tests