Update updater to v2.0.3 (build 177) with critical flag

[ovitrif]

Update updater release asset to point to v2.0.3 (build 177) with critical: true to force users on old builds to update.

Description

• Bump updater version from v2.0.2 (build 176) to v2.0.3 (build 177)
• Set critical: true to enable the blocking update screen
• Update notes URL to point to the correct bitkit-android release tag
• Update pub_date to current release timestamp

Preview

N/A — metadata-only change.

QA Notes

After merging, the release asset needs to be replaced:

gh release delete-asset updater release.json --repo synonymdev/bitkit-android --yes
gh release upload updater .github/release.json#release.json --repo synonymdev/bitkit-android

Then verify:

curl -sL https://github.com/synonymdev/bitkit-android/releases/download/updater/release.json | python3 -m json.tool

Should return "version": "v2.0.3" with "critical": true.