Add external plugin tmforge (#2991)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

.github/plugin/marketplace.json

@@ -1728,6 +1728,37 @@
       "description": "Inspect a repository, improve Tiny Tool Town readiness, submit its listing issue, and launch remediation work.",
       "version": "1.0.2"
     },
+    {
+      "name": "tmforge",
+      "description": "The Strider agent that comes with the tmforge plugin adds evidence-backed STRIDE threat modeling to GitHub Copilot, with structured risk assessment, deterministic validation, and Markdown reports. Optional tmforge integration supports creating, updating, and verifying Microsoft Threat Modeling Tool (.tm7) models.",
+      "version": "0.11.0",
+      "author": {
+        "name": "Mark Dalton Gray",
+        "url": "https://github.com/Hacks4Snacks"
+      },
+      "repository": "https://github.com/Hacks4Snacks/tmforge",
+      "homepage": "https://github.com/Hacks4Snacks/tmforge/tree/main/plugins/tmforge",
+      "license": "MIT",
+      "keywords": [
+        "data-flow-diagrams",
+        "risk-assessment",
+        "security-review",
+        "stride",
+        "strider",
+        "threat-modeling",
+        "threat-modeling-as-code",
+        "tm7",
+        "tmforge",
+        "trust-boundaries"
+      ],
+      "source": {
+        "source": "github",
+        "repo": "Hacks4Snacks/tmforge",
+        "path": "plugins/tmforge",
+        "ref": "v0.11.0",
+        "sha": "8c22d85c4cb65f416c228bb2a73ae9f364aa549b"
+      }
+    },
     {
       "name": "token-pacman",
       "source": "plugins/token-pacman",