Add transparent portrait avatars for market digital employees (#202)

The catalog previously showed opaque icons or text fallbacks for the
seven digital employees, and source-pointer installs could still get
different avatars. This updates every catalog card to a 512×512
transparent portrait, bumps the listed releases, and pins the six source
repositories to commits that include the matching AgentFS avatar.

Validation: `validate_catalog_metadata.py --require-complete` (0
errors), `validate-i18n.py` (0 errors), and `translate.py --check`. All
seven WebP files have an alpha channel with fully transparent pixels and
are below 50 KB each.

manifest.json

@@ -1,6 +1,6 @@
 {
   "name": "DesireCore Official Market",
-  "version": "1.5.4",
+  "version": "1.5.5",
   "schemaVersion": "1.1.0",
   "supportedLocales": [
     "zh-CN",
@@ -32,7 +32,7 @@
     "totalAgents": 7,
     "totalTeams": 2,
     "totalSkills": 73,
-    "lastUpdated": "2026-09-29"
+    "lastUpdated": "2026-09-30"
   },
   "features": [
     "curated-index",