Replace swaylock with gtklock; centralise theme palette

- Replace swaylock with gtklock (username + password form lockscreen)
- Add gtklock/config.ini and gtklock/style.css (Tomorrow Night theme)
- Update niri keybindings and swayidle to invoke gtklock -d
- Update packages.txt: swaylock -> gtklock
- Update install.sh: add AUR helper detection (yay/paru), symlink gtklock configs
- Add theme/colors.css (CSS custom properties) and theme/colors.json
- Update waybar/style.css, wofi/style.css, gtklock/style.css to import shared palette
- Update README.md with project summary and component table
- Add ARCHITECTURE.md and CLAUDE.md

wofi/style.css

@@ -1,29 +1,31 @@
+@import url("../theme/colors.css");
+
 * {
   font-family: JetBrainsMono Nerd Font;
   font-size: 14px;
 }
 
 window {
-  background-color: rgba(29, 31, 33, 0.96);
-  border: 1px solid #373b41;
+  background-color: var(--tn-bg-a96);
+  border: 1px solid var(--tn-bg-high);
   border-radius: 12px;
-  color: #c5c8c6;
+  color: var(--tn-fg);
 }
 
 #input {
-  background-color: #282a2e;
-  color: #c5c8c6;
-  border: 1px solid #373b41;
+  background-color: var(--tn-bg-alt);
+  color: var(--tn-fg);
+  border: 1px solid var(--tn-bg-high);
   border-radius: 8px;
   padding: 10px 14px;
   margin: 12px 12px 6px 12px;
   outline: none;
   font-size: 15px;
-  caret-color: #81a2be;
+  caret-color: var(--tn-blue);
 }
 
 #input:focus {
-  border-color: #81a2be;
+  border-color: var(--tn-blue);
 }
 
 #inner-box {
@@ -46,17 +48,17 @@ window {
 }
 
 #entry:selected {
-  background-color: #282a2e;
-  border: 1px solid #81a2be;
+  background-color: var(--tn-bg-alt);
+  border: 1px solid var(--tn-blue);
   outline: none;
 }
 
 #text {
-  color: #c5c8c6;
+  color: var(--tn-fg);
 }
 
 #text:selected {
-  color: #81a2be;
+  color: var(--tn-blue);
   font-weight: bold;
 }