refactor: rename Chrome references to Chromium

- Rename hook file: 0060-install-chrome -> 0060-install-chromium
- Update all logs and comments to say "Chromium" instead of "Chrome"
- Rename chromeStatus -> chromiumStatus in daemon
- Update UI to show "Chromium Browser" instead of "Chrome Browser"
- Update documentation (readme.plan.md, readme.hints.md)

Note: Binary paths (/opt/chromium/chrome) remain as the actual
Chromium executable is named "chrome"

ecoos_daemon/ts/ui/server.ts

@@ -201,8 +201,8 @@ export class UIServer {
           Sway Compositor
         </div>
         <div class="stat">
-          <span class="status-dot" id="chrome-status"></span>
-          Chrome Browser
+          <span class="status-dot" id="chromium-status"></span>
+          Chromium Browser
         </div>
       </div>
       <div class="card">
@@ -252,8 +252,8 @@ export class UIServer {
       // Services
       document.getElementById('sway-status').className =
         'status-dot ' + (data.sway ? 'running' : 'stopped');
-      document.getElementById('chrome-status').className =
-        'status-dot ' + (data.chrome ? 'running' : 'stopped');
+      document.getElementById('chromium-status').className =
+        'status-dot ' + (data.chromium ? 'running' : 'stopped');
 
       // System info
       if (data.systemInfo) {