feat: apply Nord colorscheme to powerlevel10k prompt

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.p10k.zsh

@@ -37,14 +37,15 @@
   # Zsh >= 5.1 is required.
   [[ $ZSH_VERSION == (5.<1->*|<6->.*) ]] || return
 
-  # Prompt colors.
-  local grey='242'
-  local red='#FF5C57'
-  local yellow='#F3F99D'
-  local blue='#57C7FF'
-  local magenta='#FF6AC1'
-  local cyan='#9AEDFE'
-  local white='#F1F1F0'
+  # Prompt colors — Nord palette.
+  # https://www.nordtheme.com/docs/colors-and-palettes
+  local grey='#4C566A'    # nord3
+  local red='#BF616A'     # nord11
+  local yellow='#EBCB8B'  # nord13
+  local blue='#88C0D0'    # nord8
+  local magenta='#B48EAD' # nord15
+  local cyan='#8FBCBB'    # nord7
+  local white='#ECEFF4'   # nord6
 
   # Left prompt segments.
   typeset -g POWERLEVEL9K_LEFT_PROMPT_ELEMENTS=(