Add plugin.json for portable plugin packaging (CW-017)

.claude-plugin/plugin.json

@@ -0,0 +1,9 @@
+{
+  "name": "project-timeline-site-creator",
+  "version": "1.0.0",
+  "description": "Provisions MPM Agile Dashboard project timelines and exports Gantt chart images for SOW embedding. Dual-mode: programmatic (called by SOW generator) or interactive (PM interview flow).",
+  "author": {
+    "name": "Message Point Media"
+  },
+  "keywords": ["gantt", "timeline", "sow", "agile-dashboard", "project", "transit", "digital-signage"]
+}