fix: encrypted data breaks Firefox — injector can't decrypt — v2.0.13

When at-rest encryption is enabled, storage.local contains encrypted
blobs. The injector reads raw storage (content script world, no
access to IndexedDB CryptoKey) and sees { _ssLocalEncrypted: true }.
It passed empty config to content.js → no mappings → no substitution.

This is why Firefox stopped working after encryption was enabled.
Chrome/Brave worked because the user hadn't set up encryption there.

Fixed: injector now detects encrypted data and asks the background
script for decrypted config via 'get:decrypted-config' message.
The background uses the Storage module (which has IndexedDB access)
to decrypt and return the data. Falls back to empty config if the
vault is actually locked.

https://claude.ai/code/session_01SWSwDfMVij53bCTNSCLMwn

manifest.firefox.json

@@ -1,7 +1,7 @@
 {
   "manifest_version": 3,
   "name": "Silent Send",
-  "version": "2.0.12",
+  "version": "2.0.13",
   "description": "Intercepts personal info and substitutes it with user-defined replacements before sending to AI services.",
   "browser_specific_settings": {
     "gecko": {