feat(emacs): Eshell stuff

- Fancify prompt
  - Shows success of last command.
  - TRAMP prefix is made distinct.
  - CWD is abbreviated.
- cd to project root (`cdp`).
- Imitate using `C-d` / send-EOF to exit.
- Opening popup shell puts user in insert state.
- Fixes TRAMP customisation.

Nicely done! }:3

users/crumb/programs/emacs/lib/syd-file.el

@@ -135,4 +135,15 @@ If FORCE-P, delete without confirmation."
      base-file
      conflict-file)))
 
+(defun syd-split-tramp-file-name (file-name)
+  "Split FILE-NAME into (TRAMP-PREFIX . LOCAL-NAME). Returns (nil . FILE-NAME)
+if FILE-NAME has no TRAMP prefix."
+  (if (tramp-tramp-file-p file-name)
+      (let* ((dissected (tramp-dissect-file-name file-name t))
+             (localname (tramp-file-name-localname dissected)))
+        (setf (tramp-file-name-localname dissected) nil)
+        (cons (tramp-make-tramp-file-name dissected)
+              localname))
+    (cons nil file-name)))
+
 (provide 'syd-file)