fix: config not reaching content.js — race condition with script removal

The data-ss-config attribute on the script tag was being removed
(via script.onload) before content.js could read it. Changed approach:
inject config as a separate <script type="application/json" id="ss-config-data">
element that persists in the DOM until content.js reads and removes it.

This eliminates the race condition between script execution and onload
removal. Bump 0.9.20.

https://claude.ai/code/session_01KF4i7Ra7zCEDskxDBaNtcT

src/content/content.js

@@ -26,12 +26,13 @@
   let settings = { enabled: true, revealMode: false, showHighlights: false };
 
   try {
-    const configEl = document.querySelector('script[data-ss-config]');
+    const configEl = document.getElementById('ss-config-data');
     if (configEl) {
-      const config = JSON.parse(configEl.getAttribute('data-ss-config'));
+      const config = JSON.parse(configEl.textContent);
       mappings = config.mappings || [];
       identity = config.identity || {};
       settings = { ...settings, ...(config.settings || {}) };
+      configEl.remove(); // clean up
     }
   } catch (e) {
     console.warn('[Silent Send] Failed to parse initial config:', e);