feat(themes): add color derivation and themed app templates

Add script/omarchy-theme-color and expand omarchy-theme-set-templates to
derive a full palette from each theme's colors.toml, then render new
themed templates (shell, pi, vscode theme, gum, neovim, claude, hermes,
t3code) from it.

Adds backgrounds and palette updates for existing themes plus new themes
(last-horizon, lupine, solitude, tidewater-*, miasma, ...).

default/themed/btop.theme.tpl

@@ -11,73 +11,83 @@ theme[title]="{{ foreground }}"
 theme[hi_fg]="{{ accent }}"
 
 # Background color of selected item in processes box
-theme[selected_bg]="{{ color8 }}"
+theme[selected_bg]="{{ selection }}"
 
 # Foreground color of selected item in processes box
 theme[selected_fg]="{{ accent }}"
 
 # Color of inactive/disabled text
-theme[inactive_fg]="{{ color8 }}"
+theme[inactive_fg]="{{ muted }}"
 
 # Color of text appearing on top of graphs, i.e uptime and current network graph scaling
-theme[graph_text]="{{ foreground }}"
+theme[graph_text]="{{ light_foreground }}"
 
 # Background color of the percentage meters
-theme[meter_bg]="{{ color8 }}"
+theme[meter_bg]="{{ selection }}"
 
 # Misc colors for processes box including mini cpu graphs, details memory graph and details status text
-theme[proc_misc]="{{ foreground }}"
+theme[proc_misc]="{{ light_foreground }}"
 
 # CPU, Memory, Network, Proc box outline colors
-theme[cpu_box]="{{ color5 }}"
-theme[mem_box]="{{ color2 }}"
-theme[net_box]="{{ color1 }}"
+theme[cpu_box]="{{ magenta }}"
+theme[mem_box]="{{ green }}"
+theme[net_box]="{{ red }}"
 theme[proc_box]="{{ accent }}"
 
 # Box divider line and small boxes line color
-theme[div_line]="{{ color8 }}"
+theme[div_line]="{{ muted }}"
 
 # Temperature graph color (Green -> Yellow -> Red)
-theme[temp_start]="{{ color2 }}"
-theme[temp_mid]="{{ color3 }}"
-theme[temp_end]="{{ color1 }}"
+theme[temp_start]="{{ green }}"
+theme[temp_mid]="{{ yellow }}"
+theme[temp_end]="{{ red }}"
 
-# CPU graph colors (Teal -> Lavender)
-theme[cpu_start]="{{ color6 }}"
-theme[cpu_mid]="{{ color4 }}"
-theme[cpu_end]="{{ color5 }}"
+# CPU graph colors (Teal -> Blue -> Magenta)
+theme[cpu_start]="{{ cyan }}"
+theme[cpu_mid]="{{ blue }}"
+theme[cpu_end]="{{ magenta }}"
 
-# Mem/Disk free meter (Mauve -> Lavender -> Blue)
-theme[free_start]="{{ color5 }}"
-theme[free_mid]="{{ color4 }}"
-theme[free_end]="{{ color6 }}"
+# Mem/Disk free meter
+theme[free_start]="{{ magenta }}"
+theme[free_mid]="{{ blue }}"
+theme[free_end]="{{ cyan }}"
 
-# Mem/Disk cached meter (Sapphire -> Lavender)
-theme[cached_start]="{{ color4 }}"
-theme[cached_mid]="{{ color6 }}"
-theme[cached_end]="{{ color5 }}"
+# Mem/Disk cached meter
+theme[cached_start]="{{ blue }}"
+theme[cached_mid]="{{ cyan }}"
+theme[cached_end]="{{ magenta }}"
 
-# Mem/Disk available meter (Peach -> Red)
-theme[available_start]="{{ color3 }}"
-theme[available_mid]="{{ color1 }}"
-theme[available_end]="{{ color1 }}"
+# Mem/Disk available meter
+theme[available_start]="{{ yellow }}"
+theme[available_mid]="{{ red }}"
+theme[available_end]="{{ red }}"
 
-# Mem/Disk used meter (Green -> Sky)
-theme[used_start]="{{ color2 }}"
-theme[used_mid]="{{ color6 }}"
-theme[used_end]="{{ color4 }}"
+# Mem/Disk used meter (Green -> Teal -> Blue)
+theme[used_start]="{{ green }}"
+theme[used_mid]="{{ cyan }}"
+theme[used_end]="{{ blue }}"
 
-# Download graph colors (Peach -> Red)
-theme[download_start]="{{ color3 }}"
-theme[download_mid]="{{ color1 }}"
-theme[download_end]="{{ color1 }}"
+# Download graph colors
+theme[download_start]="{{ yellow }}"
+theme[download_mid]="{{ red }}"
+theme[download_end]="{{ red }}"
 
-# Upload graph colors (Green -> Sky)
-theme[upload_start]="{{ color2 }}"
-theme[upload_mid]="{{ color6 }}"
-theme[upload_end]="{{ color4 }}"
+# Upload graph colors (Green -> Teal -> Blue)
+theme[upload_start]="{{ green }}"
+theme[upload_mid]="{{ cyan }}"
+theme[upload_end]="{{ blue }}"
 
-# Process box color gradient for threads, mem and cpu usage (Sapphire -> Mauve)
-theme[process_start]="{{ color6 }}"
-theme[process_mid]="{{ color4 }}"
-theme[process_end]="{{ color5 }}"
+# Process box color gradient for threads, mem and cpu usage
+theme[process_start]="{{ cyan }}"
+theme[process_mid]="{{ blue }}"
+theme[process_end]="{{ magenta }}"
+
+# Graph gradient colors (spectrum shades from background to foreground)
+theme[gradient_color_0]="{{ background }}"
+theme[gradient_color_1]="{{ lighter_background }}"
+theme[gradient_color_2]="{{ selection }}"
+theme[gradient_color_3]="{{ muted }}"
+theme[gradient_color_4]="{{ dark_foreground }}"
+theme[gradient_color_5]="{{ foreground }}"
+theme[gradient_color_6]="{{ light_foreground }}"
+theme[gradient_color_7]="{{ bright_foreground }}"