chore: bump version to 7.0.0, add CHANGELOG entry

BREAKING CHANGE: command namespace rename - see CHANGELOG.md

Merged unreleased 6.0.0 content (plan-then-batch optimization) into 7.0.0.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.claude-plugin/marketplace.json

@@ -6,7 +6,7 @@
   },
   "metadata": {
     "description": "Project management plugins with Gitea and NetBox integrations",
-    "version": "5.10.0"
+    "version": "7.0.0"
   },
   "plugins": [
     {