feat: Add Everforest-Dark theme (#835)

* Add theme: everforest-dark (default)
sourced from: https://github.com/sainnhe/everforest

* Fix merge conflict

* Update docs/themes.md
Add everforest-dark theme example

---------

Co-authored-by: Jonah Lawrence <jonah@freshidea.com>

Author: R055A

docs/themes.md

@@ -169,6 +169,7 @@ Note: Theme names provided are case-insensitive and any use of underscores will
 |           `vitesse`           |                 ![image](https://github.com/user-attachments/assets/baa2fa20-36ea-4158-befc-79c21f102f87)                  |
 |         `nord-aurora`         |                 ![image](https://github.com/user-attachments/assets/d61bf5c3-66f2-4c02-bd9d-30bf1be47c97)                  |
 |          `dark-aura`          |                 ![Image](https://github.com/user-attachments/assets/14889d0e-26db-4fa6-8026-6312c9b4636e)                  |
+|       `everforest-dark`       |                 ![image](https://github.com/user-attachments/assets/45a4e0a0-d330-4233-9d76-89003e59bb31)                  |
 
 ### Can't find the theme you like?
 

src/themes.php

@@ -2069,6 +2069,19 @@
         "dates" => "#BD976A",
         "excludeDaysLabel" => "#758575DD",
     ],
+    "everforest-dark" => [
+        "background" => "#2D353B",
+        "border" => "#4F585E",
+        "stroke" => "#4F585E",
+        "ring" => "#A7C080",
+        "fire" => "#A7C080",
+        "currStreakNum" => "#D3C6AA",
+        "sideNums" => "#A7C080",
+        "currStreakLabel" => "#D3C6AA",
+        "sideLabels" => "#A7C080",
+        "dates" => "#9DA9A0",
+        "excludeDaysLabel" => "#9DA9A0",
+    ],
     "nord-aurora" => [
         "background" => "#4C566A",
         "border" => "#8FBCBB",