release: v0.2.4 - fix icon loading (proper version bump)

This is a proper version bump from v0.2.3 to v0.2.4 after discovering that
v0.2.3 was already published on Artifact Hub with a different tarball checksum.

Replace all Material-UI icon imports with Iconify equivalents to fix plugin loading.
Headlamp provides @iconify/react as a global, not @mui/icons-material.

Icon mappings:
- ErrorOutline → mdi:alert-circle-outline
- ContentCopy → mdi:content-copy
- Visibility → mdi:eye
- VisibilityOff → mdi:eye-off
- CheckCircle → mdi:check-circle
- Error → mdi:alert-circle
- Warning → mdi:alert
- Add → mdi:plus
- Delete → mdi:delete

Also fixed test-setup.ts lint errors (unused parameters).

Tarball checksum: SHA256:49062f6e9f68de49b83d53176d0bc09ce632d3df11e3397459342f51f6282131

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

headlamp-sealed-secrets/package.json

@@ -1,6 +1,6 @@
 {
   "name": "headlamp-sealed-secrets",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "description": "Headlamp plugin for Bitnami Sealed Secrets - manage encrypted Kubernetes secrets",
   "files": [
     "dist",