chore(themes): Simplify theme initialization and setup

I've been using doom-themes' doom-vibrant for long enough now that I'm
certain I won't be moving away from it anytime soon. So let's simplify
and strip away all other theme setup stuff.

modules/editor/siren-doom-modeline.el

@@ -0,0 +1,25 @@
+;;; siren-doom-modeline.el --- jimeh's Emacs Siren: doom-modeline theme.
+
+;;; Commentary:
+
+;; Setup for doom-modeline theme.
+
+;;; Code:
+
+(use-package doom-modeline
+  :hook (after-init . doom-modeline-mode)
+
+  :custom
+  (doom-modeline-bar-width 3)
+  (doom-modeline-buffer-encoding nil)
+  (doom-modeline-buffer-file-name-style 'truncate-with-project)
+  (doom-modeline-buffer-modification-icon t)
+  (doom-modeline-buffer-state-icon t)
+  (doom-modeline-checker-simple-format t)
+  (doom-modeline-enable-word-count t)
+  (doom-modeline-height 25)
+  (doom-modeline-minor-modes t)
+  (doom-modeline-vcs-max-length 24))
+
+(provide 'siren-doom-modeline)
+;;; siren-doom-modeline.el ends here

modules/themes/siren-doom-themes.el

@@ -0,0 +1,79 @@
+;;; siren-doom-themes.el --- jimeh's Emacs Siren: doom-themes.
+
+;;; Commentary:
+
+;; Setup for doom-themes.
+
+;;; Code:
+
+(require 'siren-all-the-icons)
+(require 'siren-doom-modeline)
+
+(use-package doom-themes
+  :custom
+  (doom-themes-enable-bold t)    ; if nil, bold is universally disabled
+  (doom-themes-enable-italic t)  ; if nil, italics is universally disabled
+  (doom-themes-treemacs-theme "doom-colors")
+  (doom-themes-treemacs-enable-variable-pitch nil)
+
+  (doom-nord-light-brighter-comments nil)
+  (doom-nord-light-brighter-modeline nil)
+  (doom-nord-light-comment-bg nil)
+  (doom-nord-light-padded-modeline nil)
+
+  (doom-vibrant-brighter-comments nil)
+  (doom-vibrant-brighter-modeline nil)
+  (doom-vibrant-comment-bg nil)
+  (doom-vibrant-padded-modeline nil)
+
+  (nlinum-highlight-current-line t)
+
+  :config
+  ;; By default load the doom-vibrant theme.
+  (siren-doom-vibrant)
+
+  ;; Enable flashing mode-line on errors
+  (doom-themes-visual-bell-config)
+
+  ;; Configure treemacs styling
+  (doom-themes-treemacs-config)
+
+  ;; Corrects (and improves) org-mode's native fontification.
+  (doom-themes-org-config)
+
+  :init
+  (defun siren-doom-vibrant ()
+    (interactive)
+    (load-theme 'doom-vibrant t)
+    (siren-doom-themes-overrides))
+
+  (defun siren-doom-nord-light ()
+    (interactive)
+    (load-theme 'doom-nord-light t)
+    (siren-doom-themes-overrides))
+
+  (defun siren-doom-themes-overrides ()
+    ;; Override some of doom-vibrant's colors.
+    (set-face-foreground 'font-lock-variable-name-face (doom-lighten 'blue 0.25))
+    (set-face-foreground 'vertical-border (doom-darken 'vertical-bar 0.1))
+    (set-face-background 'vertical-border (doom-darken 'vertical-bar 0.1))
+
+    (when (not (version< emacs-version "27.0"))
+      (set-face-foreground 'fill-column-indicator (doom-lighten 'base3 0.10)))
+
+    (with-eval-after-load 'diff-hl
+      (set-face-foreground 'diff-hl-insert (doom-blend 'vc-added 'bg 0.7))
+      (set-face-background 'diff-hl-insert (doom-blend 'vc-added 'bg 0.2))
+      (set-face-foreground 'diff-hl-delete (doom-blend 'vc-deleted 'bg 0.7))
+      (set-face-background 'diff-hl-delete (doom-blend 'vc-deleted 'bg 0.2))
+      (set-face-foreground 'diff-hl-change (doom-blend 'vc-modified 'bg 0.7))
+      (set-face-background 'diff-hl-change (doom-blend 'vc-modified 'bg 0.2)))
+
+    (with-eval-after-load 'hideshowvis
+      (set-face-foreground 'hideshowvis-hidable-face (doom-color 'base7)))
+
+    (with-eval-after-load 'fill-column-indicator
+      (setq fci-rule-color (doom-lighten (doom-color 'base3) 0.10)))))
+
+(provide 'siren-doom-themes)
+;;; siren-doom-themes.el ends here