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/opencode/config.json

@@ -1,12 +1,13 @@
 {
   "$schema": "https://opencode.ai/config.json",
+  "instructions": ["AGENTS.md"],
   "provider": {
     "openwebui": {
       "npm": "@ai-sdk/openai-compatible",
       "name": "OpenWebUI",
       "options": {
         "baseURL": "https://ai.zamudio.dev/api",
-        "apiKey": "sk-777ecee5bc6f498bbd2c01b26677526c"
+        "apiKey": "{env:OPENWEBUI_API_KEY}"
       },
       "models": {
         "Qwen3.6-35B-A3B": {