chore: bump version to 1.5.6

- Fix NIP-04 encrypt/decrypt (Buffer removal in nostr-crypto-utils)
- Fix signEvent (accept Uint8Array private keys)
- Fix CSP inline script violation in sidepanel
- Fix postMessage origin for file:// pages
- Add extension test page at docs/test.html
- Hide Experimental button

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: vveerrgg

package.json

@@ -1,6 +1,6 @@
 {
     "name": "nostrkey",
-    "version": "1.5.5",
+    "version": "1.5.6",
     "description": "Nostr key manager and signer for web apps. Securely store your private keys and sign events without exposing them to websites.",
     "source": [
         "background.js",

src/manifest.json

@@ -3,7 +3,7 @@
     "default_locale": "en",
     "name": "__MSG_extension_name__",
     "description": "__MSG_extension_description__",
-    "version": "1.5.5",
+    "version": "1.5.6",
     "author": "Humanjava Enterprises Inc",
     "homepage_url": "https://nostrkey.com",
     "icons": {