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.

agents/tender-review-assistant/entry.json

@@ -7,7 +7,7 @@
     "onboarding",
     "multi-agent"
   ],
-  "latestVersion": "0.2.1",
+  "latestVersion": "0.2.2",
   "maintainer": {
     "name": "DesireCore Official",
     "verified": false
@@ -19,7 +19,7 @@
     "kind": "git",
     "repoUrl": "https://github.com/desirecore-agent/tender-review-assistant.git",
     "repoBranch": "main",
-    "ref": "8484c57e430108b3e361f328b2e31f364e92c630"
+    "ref": "d58ed0a0de03628357e8d9fd166ba929c2c275ba"
   },
   "requiredClientVersion": "10.0.155",
   "i18n": {
@@ -31,5 +31,12 @@
       "name": "Tender Review Assistant",
       "shortDesc": "Prepare review materials, clarify outcome goals and hand off to the tender review team."
     }
+  },
+  "avatar": {
+    "t": "标",
+    "bg": "linear-gradient(135deg, #007AFF, #005ECB)",
+    "image": {
+      "path": "assets/avatar.webp"
+    }
   }
 }