unify color palette, harden shikane service, misc sway/opencode updates

sway:
- config: re-apply shikane profile after every reload
  (exec_always shikanectl reload); restart waybar on reload
  (exec_always pkill+waybar); enable default_border pixel 2;
  add tlpctl power-saver at startup
- keybinds: disable floating_modifier (was "$mod normal") -
  experiment for windows popping out via accidental mod+click
- windows: case-insensitive pydm title match for floating rule
- swayfx + waybar style: unified 5-color palette (base00-0F) with
  doc headers; waybar theme restyled to match the sway palette
- waybar config: scratchpad module in left bar, "S{count}" format
- new quickshell shell.qml bar

systemd user units:
- shikane.service: bind to graphical-session/sway-session targets,
  Type=simple, Restart=on-failure (2s) with start limits so crashes
  recover without giving up permanently
- new sway-session.target and its wants/ symlinks

opencode:
- load AGENTS.md as instructions (new file)
- move OpenWebUI API key from hardcoded to {env:OPENWEBUI_API_KEY}

.config/sway/config.d/windows

@@ -10,7 +10,7 @@ for_window [window_type="menu"] floating enable
 
 for_window [shell="xwayland"] title_format "[XWayland] %title"
 for_window [title="LUCID"] floating enable
-for_window [title="Pydm|pydm"] floating enable
+for_window [title="(?i)pydm"] floating enable
 for_window [title="Form"] floating enable
 for_window [title="zoom"] floating enable